Bitmart you have to send USDT (Tether) I don't believe they take US dollars. One poster in the past said Bitmart was now taking US dollars but I have not seen that. It's a Binance based coin so if you use a swap you would have to use Pancake and have some BNB in a wallet like Metamask. In the past I have funded Coinbase with US dollars and changed that to USDT to send to Bitmart. When I sell coins on Bitmart it sells them to USDT. A pain in the ass and daunting to some but once you have it wired and all the different ways to buy different coins, it gets much easier.
Bitmart has quite a few coins, including many micros. I would just send a whole bunch of UST from Coinbase and just keep it a Bitmart when you are ready to buy. Text a small amount first in case you do it wrong and send the money to a wrong address.
I just started a new crypto board to talk about cryptos, especially micro cryptos, where millionaires can be made, just by losing some zeros. Just search Micro Alt Crytos or Let's Lose Some Zeros or link in my profile. Come pay a visit. Brand new.