You can of course export your yt subscriptions as a CSV file and import them into Piped, and you can also use a difference instance to host your account/data as the one you’re using to stream the content. Did I mention built-in sponsorblock support and native apps like LibreTube?
Jellyfin never worked great for me on my older tablet and chromecast. Always struggled with either unsupported codecs or just buffering to hell. My plex server is also on somewhat limited hardware and jellyfin could never transcode fast enough, where plex has no issue.