linux runs fine on a mac. given the limited selection of hardware variations, it is less likely to run into surprises. as far as i could tell all peripherals on my mac are working. the boot manager refind also works well.
the only thing you need to do after installation is to configure the touchpad to support 3 mouse buttons. once that's done, linux on a mac is a great experience.
iMac Generations have been hit or miss depending on the AMD GPU that was included. I also think it'll get only harder from here on out with the T2 chips etc.
Installed Ubuntu, which recognized the drive, but which didn't give me working WiFi. It would detect the NIC, present a list of networks, but then drop after 1-3 seconds.
It was only recently that I upgraded to a newer kernel and found that I could use the on-board wifi. (Until then I'd been using a USB-based WiFi dongle.)
I don't use touch-pad, bluetooth, etc. But just the basics "install + have wifi" were non-trivial.
Of course it might be easier now as the latest stable releases have new enough kernels that things will work more easily, but I fought and I wish I'd been able to use a generic intel-laptop.
whether this trend will hold in the future is anyones guess. you could be right. apple is certainly not out to make it easy.
i should also add that my personal experience is limited to two devices from this decade and a few older ones.
I was concerned that I might run into driver issues and such and thought to see what others have experienced in this as I have seen mixed things doing a basic Google search.