[pythonhacker69]

If privacy is a main goal, you generally can't get any more private than self-hosting. Do you plan on syncing while away from your home network? That would complicate things greatly simply due to the fact that you'd need to expose your self-hosted git instance to the Internet.

If you're fine with only syncing on your home network, using your old laptop, I don't really see any real security risks.

If you don't want to expose git directly, you can always expose a VPN server (wireguard?) to the Internet. This is the strategy I use. Then you can VPN into your home network anywhere you have an Internet connection, while still remaining relatively secure.