Vienna, overall, doesn't have the same level of merchant adoption you'll see in Prague or even Munich, but there are a few places. Check out nostr:nprofile1qyghwumn8ghj7mn0wd68ytnhd9hx2tcpzdmhxue69uhhqatjwpkx2urpvuhx2ue0qqstmwq86za404m8cknaa9z4ftuagpuy2lpkgnpqy6n4xns80jcvvrqjh4qaz here, as well as a few Latin American cafes and restaurants on nostr:nprofile1qyv8wumn8ghj7enfd36x2u3wdehhxarj9emkjmn99uq3zamnwvaz7tmwdaehgu3wwa5kuef0qqsra2ey033mkdwl5w8q0jss9ak69zafh82xsuvhwsaauw3trkq2amgvvanjv

https://btcmap.org/map#13/48.22021/16.38834

Austrian capital gains tax is insanely high (27.5%) for any BTC bought after 2021. If you use any of the major exchanges based in Austria (Coinfinity, Bitpanda) they'll automatically collect this tax if you sell through there.

When it comes to MiCA, most of the Austrian-based firms have already committed to following this, and already do tons of KYC, so I don't think this will change much.

If you mean "living" on BTC, likely the best way would be to use platforms like nostr:nprofile1qyghwumn8ghj7mn0wd68ytnhd9hx2tcpzdmhxue69uhhqatjwpkx2urpvuhx2ue0qqstpkv7ykr7fe99wxh84ef5xr5h5g3xex3d2mrgk39hz4m0n3ad93qs7k0kh or nostr:nprofile1qyxjqamnwvaz7tmzwf3zu6t0qy8zqamnwvaz7tmwdaejumr0dsqzphuxtm6gxpykk5q7a0vgxa7fpafpg6w503fejucqugj64vdjnvnykn4jst which you probably know. These platforms do use KYC, so you'll have to submit an identity document and could be on the hook for taxes if your tax residency is Austria. But for spending sats and their debit cards (or gift cards) the solutions they have are pretty good.

https://spend.bringin.xyz/signup?affiliate=XKU41UZUPU

For the few merchants I personally use that are usually small companies (barber, butcher, etc.) I've been moderately successful at getting them to accept Bitcoin, but nothing super official.

Obviously, the meetup community is great here, either Bitcoin Austria or Einundzwangzig Wien. I regret that I'm not able to join more usually because I'm traveling.

Hope this helps and happy to answer any other questions!