I read that some instances don’t allow posting on certain other instances, etc. I thought I would create an account on a smaller instance, in case this one gets too bogged down or whatever. Is there any way to sync them up?
They are completely separate, unless you use an app that allows you to add two or more accounts and then merges your feeds. Downside is that you’ll see duplicated threads if you subscribed with both, or are browsing /all.
The recent update from Thunder claims to eliminate duplicates though, see changelogs here: https://github.com/hjiangsu/thunder/releases
The app is already quite stable and useful, and comes for both Android and iOS (download below the description when you open the “assets” tab).
On desktop/browser I don’t know of any way to make this work.
You could technically regularly run https://github.com/wescode/lemmy_migrate but it will only allow your accounts to sync their subscriptions, nothing else.
They’re forever separate.