Hmm, this is a very difficult situation, BTCpay Server does allow for the processing of USDt on the Liquid Network, which isn't too hard to enable, but this is not interoperable with USDT from other chains, which makes it complicated and then involves one party having to use a swap service to get L-USDT
As for credit card, I have not seen a solution for this, the most robust workaround has been to purchase a gift card from a retail vendor and exchange that for Bitcoin, the gift card need not be from a Kazakhstan retailer it can be any code of a retailer that has demand P2P (many Romance scams use this technique) but it would be sold for a considerable discount to get any kind of funds, but its better than nothing