Thanks for the clarification. That claim seemed really off.
I’ve assumed that what you see publicly is basically what’s synced. Obv. your instance can have a few more meta details on you, like IP, device info, possibly all the exif they’ve stripped from uploaded photos, but these things aren’t in the ActivityPub outbox
Pretty much in general for me now. I gave it an honest go for six years but there were at least four instances where a server upgrade required nontrivial intervention to bring it back.
Syncthing + Keepass[DX] has been solid for me.