Not too difficult. Yeah just set it up and point at the existing folder with all the media and let it go to work. It wasn’t my first time experimenting with the both of them and yes you can run both at the same time. I did run both at one point in the past before settling on plex. I just had to download jellyfin and set it back up. One thing that I recommend doing with the both of them is to make sure that both of them only have read access to the actual media. Do this at the OS level. That way there are no accidents that effect the actual media on disk.

I just made the switch over this.

Yeah, donate to kde every now and then.