Sorry for the late reply, but I don’t know. That’s why I finally just gave up and installed Kubuntu onto an external ssd

Yep, shows how much I know, lol. I use Kubuntu so I had to install it first. Good luck though

Others will probably know more than me, but you know you have to install flatpak/flathub first don’t you?

I’ve had trouble similar to this. Maybe someone else can give you more info, but I believe you have to install grub on the other ssd as well. Also, to prevent nuking, make your bootable flash drive with windows on it, and then pull your linux ssd out of the computer before booting from your flash drive and only have your ssd in it that you want windows on

I was a Windows user up until a couple of years ago when I switched to Kubuntu and never looked back. I think after Windows 10 is gone, there will be a big uptick in Linux.