Currently the application stream in the pureOS repos is broken because it fails to search for a "strong instance" (invidious) to use to reproduce the videos.
Currently the latest commit to the application: https://source.puri.sm/todd/Stream/-/commit/a2897eec03bd7912ca8769820b12556c56dacfac fixes this issue. But there is not a new release tag.
There is a merge request to add a patch with this commit mentioned above to the PureOS package: https://source.puri.sm/pureos/packages/Stream/-/merge_requests/1
So IMO there is two ways to solve this issue with the PureOS package of Stream.
1 - Update the PureOS package of stream to the latest upstream commit. Which besides fixing this issue, might also add new features.
2 - Merge the patch https://source.puri.sm/pureos/packages/Stream/-/merge_requests/1 and just do a minor release to unbreak the Stream package in PureOS.