Well, what makes such a product high quality is highly subjective :D

But for me personally I'd love a Kanban product that can rival Notion's feature set and simplicity, can be used offline / is local-first, offers some custimzation options, does not force me into a subscription, works well on desktop (Windows) as well as on my phone (Android).

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