How to check is game region locked?

try this but i not know if it work
https://www.steamgifts.com/discussion/WeOlc/guidehow-to-find-out-if-a-game-is-region-locked

doesn't the store let you check if it will activate in your country? many stores do it, like Fanatical and Gamebillet, based on your IP

https://www.hlplanet.com/how-to-check-game-region-lock/

There is NO reliable way to tell if key is region locked or not. You can check subid restrictions, as I've described here https://www.steamgifts.com/discussion/oef08/guide-how-region-locks-work
BUT even if there is no restricted subids key still can be restricted.
This is very frustrating, but that's the way steam works - part of information is never revealed.

oh i have old Humble Choice Monthly keys and I'm afraid to sell them or give away without a region lock

I think the only way is to get accounts from different regions, buy multiple keys from the shop and try them with each account. Then you will know the exact restriction of it