It can be really hit-or-miss, and it can be really hard to debug errors like in the post.
A lot of workarounds that are suggested for various issues are also not really viable. Some of the workarounds involve turning off different power-saving modes; however, the point of enabling sleep is often to increase the amount of usable time between charges, and turning off these power-saving modes can often dramatically shorten battery life.
But getting sleep to work (even S0ix!) is not impossible.
I have a bunch of handheld AMD 7840U and AMD 8840U devices that I have installed Arch Linux on: GPD Win Max 2, GPD Win Mini, GPD Win 4, Minisforum V3, OneXPlayer X1 Ryzen. These devices were not designed with Linux support in mind. I would be very surprised if the companies that made them ever tested them with Linux. Yet with just a small amount of work (generally fiddling with `/proc/acpi/wakeup` and `/sys/devices/*/*/*/power/wakeup` to disable sources of spurious wakeups,) I have gotten essentially flawless S0ix support (… on all but the newest OneXPlayer X1 Ryzen.)
(In general, out-of-the-box stock Linux kernel support on these devices is fantastic. Touchscreens work, pen input works, wifi and Bluetooth work well. The only gap I've seen is fingerprint reader support.)
I suspect that given how small these manufacturers are (and how small their production batches must be,) there's much less extreme-customization and tight-integration of components. This is visibly evident in the form-factors of these devices, which many millimeters thicker than they might otherwise be. (Of course, these devices are primarily advertised to a gaming audience who are eager to avoid the thermal-throttling that happens with ultra-thin devices like Surface Pro…) I partially suspect that the lack of extreme-customization, the lack of tight-integration, and the smaller production batches means that the manufacturers make much more conservative choices in components. Maybe this explains the exceptional Linux support?