There have been several accomplished players from Pakistan that have played in domestic leagues in the US. There are several leagues around the country that have attracted Indian and Pakistani players to showcase their crafts there, but the number of credentialed (international) Pakistani players far exceeds the Indian players who at best have played Ranji Trophy (which I do hold in high regard as you'll see later). Players like Aizaz Cheema, Najaf Shah, and Mohammad Asif - in the pre-Covid time up to 2019 - have regularly participated over a few seasons in the Washington Cricket League (WCL) and Washington Metropolitan Cricket Board (WMCB) in the Washington DC metropolitan region. I belong to this region, am a club owner, and have had personal experience here, so I will keep my views focused mostly on what I have personally seen. There also are several domestic Pakistani players that play here.
A very brief introduction on the US cricket scene - to make it to the USA Cricket team, the players play in different cricket leagues around the country. The leagues are comprised of different clubs whose owners sponsor all participation. Many of the club owners hold stakes in the US Minor League and US Major League teams.
Here are some of the reasons why the Pakistani players have not been as many in number in the US national team:
1.
Residency requirements: The aforementioned Pakistani international players would have been a shoo-in but none of them meet the residency requirements. Asif in particular is more interested in coaching in England, and rightly so. There are many Pakistani domestic players that are queued in for getting residency, once that comes in, we'll see more Pakistani origin players in the team hopefully. Indian domestic players tapped this market before the Pakistani counterparts and established their residency status. One player of Pakistani origin - Ali Khan - would always be welcomed into the US team because he is a genuine matchwinner, but his focus seems to be T20 cricket and CPL. At this time, USA Cricket does not pay nearly as well as leagues do. In the past (10-20 years ago), however, more Pakistani origin players have represented the US than Indian origin players. The maximum participation in the US cricket team has historically been by the players from the Caribbean.
2.
Discipline: This is my personal opinion as a cricket club owner combined with chats with other club owners around the country including Pakistani club owners. Many reputed players of Pakistani origin are repeat offenders for coming late to the ground for the matches, not helping to set up the ground / pitch matting where needed (yes, we need to do that here), leaving early during the matches after their batting is done so they can make more money joining their "other team" during their match on another ground. Of course, they only do the two matches a day thing when matches start at different times during the day for different leagues with some overlap. Leagues are working aggressively to suppress this behavior with rules, so this won't be a problem going forward. There are some players of repute - and I won't take names or what they inhale - that indulge in "recreational inhalation" before, during, and after the games. Then Hukka sessions after the games are quite common where everyone is invited. There are some players of Indian origin that do the above too, but their numbers are much lower than their Pakistani counterparts.
When these things happen across the country and leagues from which the US team is eventually picked, the word goes around and people know. If the discipline issues are sorted, things could become better, not just for the Pakistani players but also for the US team which will have some quality players in their ranks.
3.
Quality: The overall quality of Indian domestic players playing here is higher than the quality of Pakistani domestic players. I am obviously not comparing players like Najaf Shah or Aizaz Cheema (both of whom didn't meet the residency requirement before getting into their mid-to-late 40s), but more like players coming from Pakistani domestics versus Indian domestics. The Indian players are far more disciplined - batters have a much better technique and adjust to the pitches much faster - and bowlers who are slower than their Pakistani counterparts but don't leak as many runs. A cursory glance at the scorecards of the games in the leagues I mentioned above will show you what I am talking about. There are several players from the Indian domestic circuit that have played here have been / are bonafide stars - players like Sarabjit Ladda, Sunny Patel, Ravi Inder Singh Mehra, Raunaq Sharma, Jasdeep Singh, Sunny Sohal, Rishi Dhawan, Atish Gawand, Milind Kumar etc. have regularly been matchwinners for their respective teams. Most of these players also play in the US Minor League, Major League, and / or the US national team.
4.
Loyalty: One thing that is not spoken much but is a personal thing is how loyal the players are to their respective clubs. Players don't realize that Club Owners hold a lot of sway in promoting players. If you as a player switch between teams frequently to get an extra $25-50 per game, then that makes the player more like a contractor than a family member, if you know what I mean. If you like someone, you will go the extra mile to promote them, but nobody likes job-hoppers.
5.
Communication: Indian players are generally better communicators and are able to represent themselves better than their Pakistani counterparts. In general, I have seen them make and maintain better relationships with Club Owners regardless of Club Owner nationality. It matters when you can communicate better, provide good input from your experience, and articulate that better so local born players (again mostly subcontinent or Caribbean ones) can understand them better - it brings everyone on the same page better. Performance obviously matters, but if two people have a similar performance, you will choose the one who everyone gets along well with better and can readily talk to.
Some stuff that I have said above is sometimes generic in nature based on my own observation and experience, you may or may not agree with it, I won't be offended

. Contrary to how the situation is between Indians and Pakistanis in the respective countries, here in the US the relations are very cordial. We spend time with each other very cordially, often watch India-Pakistan matches together, sledge the hell out of each other in all ways without getting personal, disagree with each other many times, and still remain friends the morning after. Life is much better this way. So I would ask you to not give this post a nationalistic flavor and just read it as an opinion from someone that you may or may not agree with. Don't unload on me

Cheers!