git-remote-gcrypt is a git remote helper to push and pull from repositories encrypted with GnuPG, using a custom format
Supported backends are local, rsync:// and sftp://, where the repository is stored as a set of files, or instead any where gcrypt will store the same representation in a git repository
The aim is to provide confidential, authenticated git storage and collaboration using typical untrusted file hosts or services.

Tested: it works fine and is very easy to setup:

git remote add gitcrypt gcrypt::git@...
git config user.signingkey ...
git config gcrypt.participants ...
git push gitcrypt master

To encrypt only SOME files in a git repo, better look at git-crypt

TL;DR version of lessons from the post:

1. Writing open source software can be very rewarding in ways you can’t predict
2. Be in it for the long haul
3. Ship it and ship regularly
4. Have broad, open-ended goals
5. If you care enough, you’ll find the time
6. No one cares about your unit test coverage
7. There’s no shame in marketing
8. Clear it with your employer
9. Foster community
10. Keep it enjoyable

Source: https://www.reddit.com/r/Python/comments/smta85/lessons_learned_from_my_10_year_open_source/