I think one might argue even a VPN might be enough. Theoretically someone might be European and can have American card or any other countries cards and it would generally be okay.

So the only thing you kind of need to figure out is VPN and ProtonVPN provides free vpn service which does include EU servers access as well

I wonder if Claude Code or these AI services block VPN access though.

If they do, ehh, just buy a EU cheap vps (hetzner my beloved) and call it a day plus you also get a free dev box which can also run your code 24x7 and other factors too.