most are still stuck to ipv4 and being NATted to oblivion, instead of adopting newer ipv6

The first thing I do with my isp provided modem is set it to bridge mode.

Contact your ISP, and request for CGNAT removal. Unless you live in Germany.

Does STUN no longer work to allow port-forwarding when needed by P2P applications?

Assuming you mean IPv4 CGNAT: IPv6.

I don't see that where I live - some ISPs offer port forwarding, some don't. Some just give you IPv6 with ports unlocked manually in router config

It still works for now, but it would be neat if only the uploading part needed to go through a VPN since that's the bit you can get in trouble for.

Would need a way of obfuscating the uploaders and downloaders though.

I use Proton VPN which has port forwarding

Rent a seed box. That's the best solution for everyone.

Port forwarding is premium? On what exactly? I must be out of the loop...

Anti Commercial-AI license