Unless they are taken down, it won't be an issue. Given they've existed for a good while it's unlikely to cause a problen. Even then, hopefully they delete your payment details after a few weeks/months.
If not, paying = assisting a criminal organisation could be a crime depending on your jurisdiction. But most of the time customers aren't prosecuted, but that can change at any point in time.
https://fwupd.org/lvfs/devices/
In the devices list of lvfs/fwupd there's a bunch of controllers supported. But it seems like it's mostly their retro controllers. XBox-style controllers like their Ultimate C etc. are not supported.