Plex is probably the easiest and most convenient, I think jellyfin is viable too, but I don’t use it.

If you’ve got the money, Roon or Audirvana are the gold standard of self hosted music

If you want something similar, but free, look into things like volumio or subsonic based solutions.

Hardware transcoding on SBCs is generally not fantastic, you’re gonna want to look for one that has VAAPI/VDPAU support or you’re gonna be looking at 100% CPU for half a day to transcode a film, which will make your other services effectively unavailable at the time.

I used to run my Plex server on a Pi4 with 4GB of ram and it basically crashed any time transcoding kicked in, I swapped to an intel NUC so I could get QuickSync for transcoding.

I’ll point out though, every SBC you’ve listed has usb, which is all you need for an external disk. If you’re worried about size, I’ve got a 5tb external drive that’s about 5cm², which is basically the footprint of any SBC you could use in this scenario

Okay fair play, if you’re doing this super short term it could make sense. Though I question what SBC you’re using that’s capable of transcoding video but not the ability to plug in an external drive.

$12/m for your 2TB of usage would make sense for maybe 5 months before it would be cheaper to buy an external disk—and of course that storage is gone once that time is up, Vs a hard disk which will probably last you a decade or so

I’m not sure about transparently, that’s more in the tdarr wheelhouse I’d say. You’d dump the files into a monitored folder and it will replace it with a version transcoded to your specification.

Transcoding video takes a fair bit of time and energy too FWIW, so you’re going to need enough local storage to handle both the full size and smaller one.

I have to question the idea though, cloud storage is always more expensive than local for anything remotely non-temporary, and transcoding a load of video all the time is going to increase your energy bills. If you have any kind of internet bandwidth restrictions that’s gonna factor in too.

I’d say it would be better to save up for a cheap external hard drive to store your video on. For a year’s subscription to a cloud storage service that would provide enough space for a media library, you could probably get twice the amount of storage forever.

Unless you’ve got raw uncompressed video, any kind of transparent compression like you describe is only going to cost you in energy bills for no benefit. Most video is already compressed with specialised video compression as part of the file format, you can’t keep compressing stuff and getting smaller files.

The alternative is a lossy compression, which you could automate with some scripts or a transcoding tool like tdarr. This would reduce the quality of the video in order to reduce the file size