I am currently working on packaging vikunja - however, my freetime doesn't allow me to spend too much time on it.
I have pushed a "working" version to the cloudron git: https://git.cloudron.io/philkrylc/vikunja-app
The basic configuration is done, postgres and redis are also configured and working. I cannot get mail to work, so those parts are commented out. Vikunja has no LDAP feature, so at the moment it comes with its own user management.
As this is my first app I would call it a PoC - it is not even close to perfect. Please feel free to improve it so we can get Vikunja on cloudron.