Stremio, for the “illegal” part of it, is just torrenting without sharing. It’s awfully convenient, but you’re ditching the very point of torrents with it.
AFAIK, the only limitations by using it as a guest is the inability to save movies… Which is extra stupid since you are torrenting them, but hey, it’s free so you are the product.
If what you are looking for is a nice interface to all your content, Kodi is the OG here.
FWIW on stremio you can click create account then “guest login” to skip making an account
also popcorn time
Some components are open source (stremio-web for example): https://github.com/orgs/Stremio/repositories
There maybe many and there maybe none, depending on your usecase and the effort you are willing to make in setting them up, and your device. Are you willing to self host? What device are you using? How much automation do you want?
Opensource in what way? It’s just torrenting material and forwarding it to you, if you want to make your own personal private media streaming service you invest in storage and “aquire” media however you want to serve out using something like Jellyfin.
