Semi-related for people whose distros don't package deno, I installed deno in a distrobox and exported it with distrobox-export and yt-dlp picked it up just fine from my $PATH. Before I did so, running yt-dlp gave the following error:
WARNING: [youtube] No supported JavaScript runtime could be found. YouTube extraction without a JS runtime has been deprecated, and some formats may be missing. See https://github.com/yt-dlp/yt-dlp/wiki/EJS for details on installing one. To silence this warning, you can use --extractor-args "youtube:player_client=default"