There's probably a good reason they aren't operating in the US.

We are licenced and regulated by the FCA in the UK and the NBB in the EU – two trusted financial authorities that also regulate Wise. We therefore have to meet the expected high standards both authorities require from us, especially in terms of KYC&AML.

Famous last words.

Fraud. What if you are required to return the inward deposit but cannot obtain the corresponding outward transaction. Or you can but lose money on the rate.

Bank transfers being reversible is the reason for the difficulty buying crypto at least years ago, maybe it is easier now.

FX services in my experience have a lot of staff and ask a lot of questions even for established accounts. Also the banks ask a lot of questions (although that is to the benefit of the FX service reducing the likelihood of fraud hitting the FX)