I haven’t had any issues with sync - I often have to work in areas without wifi/data and I was amazed at the LAN aspect of syncing between my laptop & phone using hotspot with this app, The backup feature is great for peace of mind aswell.

One thing to note is that it seems to sync (encrypted) to their server, with no option to turn it off [yet]

Mullvad, ivpn

I use anytype!

Theres a bit of a learning curve but it even has local sync (you can sync your phone/laptop even without WiFi using hotspot)

https://anytype.io/