Technically yes you could hire an attorney, file a lawsuit and attempt to get money back but if you are owed say $5,000 most attorneys are not going to take that case on contingency and you would probably spend $5,000 or more (and possibly several years of litigation) on an atty retainer and hourly Atty Billings
You could possibly sue the brokerage firm that the US based firm had their accounts with. In the case of Topstep and E2T I dont know who their broker is that holds the account(s). Then the question is ---are the accounts solely in the tryout funding company's name or is your name also listed on the brokerage account statement
In the case of FTMO you could do that as well--sue the broker the account(s) are with which in FTMO's case is https://www.lmax.com
Sure how much do you think its going to cost to sue an overseas company ? Lmax is a UK based, not US. I'll give you a hint - way more than $5K.
US laws are clear if you're a US person - i rather choose the path of least resistance.