I just pushed MiTubo 0.3 to the Ubuntu Touch app store, added a link to the AppImage package in the Releases page and later during the night the Launchpad builders should import it and build it for Ubuntu 18.04 and 20.04.
This release adds basic support for RSS feeds. One just needs to type the address of an RSS (or Atom) feed in the search bar and the "Search" button will transform itself into a "Subscribe" one. Unfortunately no discovery mechanism is implemented yet, so one cannot just enter the address of a webpage and expect MiTubo to find the feed URL(s); I plan to bring that in a future release, but for the time being you'll have to enter the exact address of the RSS feed.
Also, there's no tracking of which videos are new and which ones have been already watched. Again, that's material for a next release.
But as a start, feed are remembered in the configuration, and the next time you open up MiTubo you'll see them in the main page, and the most recent videos will be shown.
As usual, you're welcome to report issues in gitlab.