Just checked out Seal. My impression:

It uses the same backend as MeTube (yt-dlp), so they have the same capability as far as website support and file formats.

Seal looks like a good option if you don’t have access to your home network or if you don’t have a dedicated machine to host things.

I still prefer MeTube because it’s a web UI that I can access from any machine. I use a VPN to stay connected to my house so I could still use MeTube while away.

Is it primarily for iPhone users?

MeTube is just a web UI, not a phone app. It is accessible by any device that can see the local IP and port of the host machine.