Syncthing has built-in encryption and works pretty well, it's also really easy to use. I have been using it for some time with several instances and never had a problem, it requires more CPU though, so some old raspies had a hard time working with my big photos folder (800GB) when encrypted. On instances that are not encrypted, the full HDD is encrypted (the option you have when installing Linux).

Not sure how secure it is, but from the docs: Encryption is XChaCha20-Poly1305 and AES-SIV with a key derived from the password and folder ID using scrypt. Considering how polished, huge user base and how much attention to detail Syncthing has, I trust it's good enough for my needs.