The really simple setup for a single user is just a SSH server with access to storage and the git command. Assuming your laptop and desktop have SSH access to server, you can just:

ssh server git init --bare somerepo
cd somerepo
git remote add server server:somerepo
git push --set-upstream somerepo master #(or main)

For something slightly higher-tech, I recommend going with Forgejo (the fork of Gitea). It is really easy to set up and low maintainance.

Avoid GitLab for small setups, it is fairly resource hungry.