[xet7]

It's possible to self-host WeKan kanban https://wekan.github.io and use it like PWA https://github.com/wekan/wekan/wiki/PWA at Windows, Android, iOS etc, more info at https://wekan.team/app/ , where is my app without Admin access at my server, but with with that PWA wiki page similar is possible.

But WeKan does not rival Notion feature set. For that, maybe AFFiNE https://news.ycombinator.com/item?id=44165373