Hello, everybody. We are considering testing Wekan. Is there also an Android-App for that?

Wekan Snap includes full server with database, so Wekan Snap can be installed to local network to server that does not have ports open to Internet. If there is open ports to Internet, Caddy webserver included in wekan provides automatic Let's Encrypt SSL cert, or you can use your own SSL cert, as documented at Wekan GitHub wiki. Also other webservers like Nginx and Apache can be used in front of Wekan to provide SSL.

Wekan uses Meteor web framework www.meteor.com so that's Javascript on frontend and backend using nodejs and mongodb

Snap is sandboxed with strict confinement, Wekan code can not access files outside of /var/snap/wekan directory

All Wekan data including files is stored to Wekan MongoDB database. You can also store files to harddrive directly instead, you see setting for that with command: wekan.help | less

So for example create directory /var/snap/wekan/common/attachments and add setting with snap command

Wekan does not currently have offline functionality.

other than, if server is on your laptop or local network server

but cards of board can not currently be edited offline

As can be seen from my Roadmap https://boards.wekan.team/b/D2SzJKZDS4Z48yeQH/wekan-open-source-kanban-board-with-mit-license , currently I'm working on adding Assignee field like Jira, it's mostly already implemented. Also drag handles for more mobile usability is nearly done, some parts still do not have drag handles - other parts of card can be used to drag board up and down with finger, only drag handles move cards and lists.

After those, I will implement notification drawer like Trello.

For Wekan, Friend etc installs, features, fixes etc there is also my Commercial Support available https://wekan.team

All Wekan version history is at ChangeLog https://github.com/wekan/wekan/blob/master/CHANGELOG.md