Option to use Nextcloud backend?
Could be interesting to use Nextcloud as an alternative backend server for this.
The Kanban app offers an API now: https://help.nextcloud.com/t/nextcloud-deck-releases-their-rest-api-congratulations/35246
And notes and note-versioning, tasks etc. might be doable through the qownnotes API: https://apps.nextcloud.com/apps/qownnotesapi
Anyways... just an idea :)