Maybe go down an update while its booting?
I was having a ton of flatpak issues recently, what solved it for me was rebasing from testing branch to stable and then after the reboot using the built in update tool. Not really sure what it did but flatpak was able to install and update after that.
And if you find lutris on flathun you should be able to click install and it will prompt bazaar to open the link


Display port to HDMI cables are pretty good