You also have individual components listed in the hardware database too. Unfortunately, it cannot be guaranteed that these will always work together (sound, network, graphics…).
Therefore, a selection function for assembling would not make sense, as one cannot declare the assembly as 100% functional.
I don’t know about Hackintosh guide, but it definitely would feel nice to see guide to build a HaikuBox.
But then, at the same time that might align to what Haiku wanting to achieve? Maybe? I don’t know. Maybe there’s already some form of guides out there.
I have several old laptops and desktops. Haiku runs more on less on all of them. If you can’t get a laptop as already suggested then I would suggest using the hardware compatability listing to choose something relatively cheap on eBay or similar.
I certainly wouldn’t buy a new laptop to run Haiku and I have had mixed experiences with dual booting. Newer systems tend to have devices for which drivers are yet to be written / ported.
Don’t fret about not knowing enough. The BeOS/Haiku books are helpful as is this forum when you get stuck.