Recommended alternatives to Firefox Sync?

I'm currently looking for an alternative to Firefox sync, preferably self-hosted.

• I'm already using Nextcloud, so something that uses it would be preferable
• I've switched to Zen, & I'm hoping for one that also works with Brave.
• prefer one that's integrated to the browser's bookmarks system & not just tied to the addon

What are your thoughts about Floccus? Are there alternatives I can explore?

And are there options that can sync extensions, and open tabs?