I'm not sure how well known it is, but YouTube itself has an RSS feed for each channel (well, Atom feed, most feed readers treat them interchangeably).
https://www.youtube.com/feeds/videos.xml?channel_id=XX
Where XX is the channel ID (the last component in the URL when you go to a channel).
It's actually how I consume YouTube these days. It's a slightly orthogonal problem to the solution posted here, since it doesn't follow the RSS "enclosure" spec. Though my feedreader knows enough to call youtube-dl on these URLs, which is fragile at best, but works for me.
And combine this with NewPipe[1] and there's no reason to miss YouTube app at least on android.