Well, since atomic swap is not really possible in this case, the answer is no. But maybe a reasonable setup is possible.

I would think in this direction: the machine keeps private keys for multiple Liquid wallets with standard amounts of USDT. The user puts in $10, gets a key for 10 USDT and can sweep in on-chain.

To those who will say "but USDT is a shitcoin": try to make an exchanger without any way of knowing the rate since you're offline.

Yes, but you also need to be running a server somewhere else.

Look at the LNURLPOS.