For low-resource usage, Forgejo has a good reputation: https://forgejo.org

ie you can run it effectively on even a Raspberry Pi

Remember to ensure you have proper backups regardless of whatever you decide to host it on. :)

i had a gitea instance in a beaglebone black! Self hosting can have really low requirements (now it's a much beefier banana pi R3 router, but there are many containers running on it)