I have used these: https://www.crucial.com/products/ssd/portable-ssds
They work great.
I also have a few m.2 nvme/sata enclosures.
I like this one the most - https://www.amazon.com/gp/product/B08RVC6F9Y
I basically just reuse old m.2 SSDs in them and they are functionally the same (and potentially more reliable) as the portable SSDs you can buy.

What do you mean? I have used chromecast with Jellyfin many times.