If his country or region is banned, can he transfer the ownership of that account to someone else to meet up with the rules and KYC?
No, read below my post.
Does the KYC with a nationality from the banned country lock your account and you can't do anything about it or is it just a geotagging, IP ban?
It will be tough issues and mostly the exchanges wouldn't care anything or very slow to respond the case since anyone should understand TOS can be changed anytime and leaving your coins on exchanges always not recommendable. So it's the exchange right to follow their rules.
What about OP trying to log in to his account in a different country that doesn't ban crypto? Using VPN? Sell his account to someone else from a different country?
Using VPN to hide your jurisdiction is illegal and abusing the exchange, your account might got terminated and your funds will be confiscated, perhaps they will ask your KYC first since their system will flagged your IPs are different. According to their TOS, you're not allowed to sell your account.
You are not permitted to transfer your account to a third party.