Wouldn't it work if you stream the resulting video as a Youtube Live stream?
You would have to set a stream up in the Youtube creator web page, in order to get a streaming key and with it, a full RTMP URL.
Then in FFmpeg, use "-f rtmp://...your target url" as output. Youtube will stream a live video (which you can hide as "unlisted") and afterwards, the video will remain in the channel as a VOD.
MoviePy is pretty committed to working with files, and I couldn't quickly figure out PyAV pts/dts for the concat even though the files were all exactly the same format.
I was hoping to combine lengthy h264 .mts video files chopped at 4GB by the video camera into one YouTube upload without duplicating on disk first.
Edit: also maybe some simple filters/ML to detect anything interesting to clip and merge into a time lapse.