My recommendation would be to get an account on Gemini and purchase crypto through them and then transfer it off to a hardware wallet like Trezor. Since its beginning Gemini has always tried very hard to be fully compliant with US law and regulations, which is not the case for some other popular crypto exchanges. Also, I've been happy with their customer service and responsiveness. At one point I had an issue with a trade executing too slowly. I opened a ticket with them and the team ultimately resolved the issue by issuing the trade at the lower price I saw.

In regards to the hardware wallets, I'd buy 2 Trezors and store them in separate locations, so that if something happens to one, then you can still quickly and easily access your coins with the other one. (If you don't do this, then if you lost your Trezor for some reason, you'd have to order another one and wait for it arrive before you could recover and access your crypto)