As I already mentioned as a user I don’t care about backend. I can use Postgres, so my question was wider than just SQLite. While your points are valid for SQLite, they are invalid for Postgres.
I will investigate how to set up Postgres server reachable from whatever and how to encrypt it.
Since you use Linux, you may already have a NAS or another machine where you can install a PostgreSQL server. You can also install it directly on your own PC. Then configure a VPN on your Windows machine and connect through that to your local network. If you don’t have a static IP from your ISP, you can use a dynamic DNS service.
A VPN connection can be strongly encrypted.
With an encrypted VPN tunnel, you don’t need to encrypt the PostgreSQL connection itself as long as the PG server is inside your local network.
On your Windows PC you can encrypt your whole disk — either with one of the open‑source disk encryption tools, or, if you have Windows Pro, Enterprise or Education, you can use BitLocker.