[noggin]

OK, so there is no perfection to be had from one single device. Is there perfection to be had by combining two (2) devices?

For me the ATV 4K is the perfect DRM streaming device, and AMLogic boxes running CoreElec play pretty much all of my locally stored content (apart from niche 4:2:2 stuff that most people don't have to worry about), though the Pi 4B is now looking interesting for this too with the latest LibreElec Nightly builds (and they are running mainline kernels, and have far better support than ODroid with their comedy warranties and support)

so pi 4b can now playback of 4k HEVC 10bit HDR videos smoothly and have the same performance as Odroid N2+ and nvidia shield pro etc?

I got a pi3b with LibreElec, it is good kodi device
but lacks 4k playback and sometimes randomly reboots 

Do you have pi 4B and is there any heat throttling issues (as reported)?

It's still quite early days for the Pi 4B and full 10-bit HDR replay - and deinterlacing has only just returned too. It's in nightlies not stable - so that tells you it's still early days. If you put a Pi 4B into a case with decent cooling (the Flirc cases use the entire case as a large passive heat sink) then temperature issues should be reduced - and throttling should only really happen on CPU-intensive tasks, which hardware accelerated replay of h.264 and h.265 mitigates - though if you have a lot of HD MPEG2 or VC-1 stuff then that may be heavier on the CPU and good case cooling will be useful for that.

I'd put the Pi 4B ahead of the ODroid C4 - not sure how it stacks up against the N2+.  The ODroids have the benefit of optional, decent quality, eMMC - which can outperform uSD card storage for large databases and quicker boot times. The Pi 4Bs have better support, are easier to get hold of from multiple suppliers with decent warranties/RMA policies, and have better third party case support etc.

In terms of the AMLogic stuff - you really have a choice with the Pi-like ODroid boards - which have truly terrible warranties from their manufacturer (who also treat people's RMAs pretty badly by all accounts) but which are well like otherwise, or Chinese Android TV boxes based on AMLogic chipsets (which come with cases, PSUs, remote controls etc.). The hardware build quality of some of these leaves a lot to be desired in some cases (cheap eMMC, poor quality heat sink solutions etc.) - so I'd take recommendations from the CoreElec forums.

As for the Vero 4K+ - at least Sam is giving you a timescale for support - the other solutions have no such guarantee?