So, this is something that is going to get worse before it gets better as HDR standards, at the moment seem to be only a suggestion and most OEM just wink at.
Even somebody that should know better like LG has been basically branding all of their 2022 model displays with “HDR” and in the case of their lower end models. most of them can only hit 250- 300 nits at best.
Specifically in your case the reason the Galaxy Book Pro looked better was due to it processing a HDR10 signal which is the minimal HDR spec and has a relatively compressed dynamic range compared to other HDR formats. The iPad Pro tries (and fails IMHO) to decode a Dolby.
And that’s not a knock against the Galaxy Book OLED either, its actually quite good (though color accuracy could be better IMHO)
My daughters Pro 12.9 does a much better job compared to my Pro 11 but it’s still not great.
A big chunk of the problem lies with Netflix as in the case of The Sandman the target device was Samsung’s Q90B series of TV’s which are their top of the line and have maximum brightness levels more than double the average consumer set.
They are even using Sandman to demo the sets in some trade shows recently.
And OTOH, something like Season 4 of Westworld on HBO has the opposite problem where you can more easily see compression artifacts such banding that buried in the murk on lesser sets.
And FWIW generally, for any display to have even a shot at properly displaying HRD content, it really needs to be certified as HDR 400 and realistically HDR1000 to have a good shot at the higher-level formats such as Dolby.
And there is just the smallest handful of computer displays out that are HDR1000 certified displays, and they are all standalone monitors. There are a few HDR400 laptop and tablet displays out there such as in the miniLED iPad Pro 12.9 and Dell’s newest XPS 13
TLDR at the moment buyer beware on any display that claims HDR especially if it doesn’t have a number or codec after it.
PS: If you want to get sense of how well or not a lot of the HDR is working on various TVs, check out the boards over at avsforum.com