I know not an ideal solution but after trying lots of foss applications, we decided to make our own solution. Other than that Nextcloud Deck is more than enough for most use cases
I only have experience with nextcloud deck. It generally works. The permissions for other users are not very intuitive. I had problems with embedding pictures.
The android app has room for a lot of improvement. Especially regarding support for markdown.
Check out Anytype! It is a local-first cross-platform app with Notion-like features, and it has a Kanban view. It is SUPER customisable, I have set it up with a PARA workflow that fits my needs.
I actually very recently tried it. I'm sure it's great but something about the UI or maybe general paradigm switch versus apps like Notion really confused me. It looks great though, so I'm sure I'll give it another go sometime when I have a bit more time to really learn it. Nonetheless, I appreciate the recommendation!