"Why should this be included in the repository? If we already offer similar software in our repository or third party, please provide information on what your proposed software does that our existing offerings don’t (differentiators)."
Stremio is similar to Kodi or Plex but it's not a media center per se, Stremio is a one-stop hub for video content aggregation. Discover, organize and watch video from all kind of sources on any device that you own. Movies, TV shows, series, live television or web channels like YouTube and Twitch.tv - you can find all this on Stremio.
Is it Open Source: Yes
"Who and how many users do you anticipate will use this software?"
Everyone who like watch movies and tv series. On March 2018 Stremio team claimed to have reached 5 millions users, someone of those maybe is using Solus.
Link to source tarball/zip file: https://github.com/Stremio/stremio-shell/archive/4.4.25.tar.gz
Stremio team release a .deb (for debian/ubuntu), a .rpm (for fedora) and a .tar.xz (for arch/manjaro) packages.
You can find those packages here: https://www.stremio.com/downloads