Which bootloader did you use? There are the 256 MB, 512MB, and 1GB variants. Try to gather log debug information from BeOS either through the startup or when it loads successfully to desktop.
Someone could set up a VM and test the scenarios…
You can run BeOS on machines significantly under 20 years old. Core2 era machines are about the latest, and even there are very limited graphics card options once you go past the AGP era - the Matrox G550 PCIE for late 90s performance (this is what I use) or a very very few nvidia cards with PCIE-AGP bridges on board.
But that era of machine will run Win10 with its onboard graphics; and R5 with the Matrox and less RAM.
Its a lot of effort to get all the right bits and very few motherboards work quite right so my ‘fast’ BeOS machine is a few generations older - but still not 20 yet. Pentium D, 512MB RAM, 120GB SATA SSD
As for the bootloader - the 768 and 1GB versions seem to be lost to time; I can only find the 512MB one.
This answer is a little off-topic but hopefully useful.
This is by design.
After Windows XP, Microsoft makes every other major release of their operating system terrible so that the users thinks that the next release is better than the previous. If they did not do this it would be very apparent that each major version is worse than the previous one and that it is by design. I guess this strategy has a name because it is used by many companies in different industries to try to hide the fact that they are deliberately making their products worse.
Windows 2000: Excellent
Windows XP: Almost excellent
Windows Vista: Terrible
Windows 7: Good
Windows 8: Terrible
Windows 10: Better than Windows 8 but worse than Windows 7, so still terrible
Windows 11: Terrible
Microsoft, like Apple, Linux (the kernel), GNU and Google, obviously has an agenda that is not good for us users. That is why I have high hopes for Haiku that are doing tings correctly for the most parts thanks to its inherited BeOS legacy. Unfortunately I believe if Haiku starts getting traction some big company will offer money to the project with some strings attached, which might not be obvious to the untrained eye, which will be the start of the demise of Haiku. This can be protected against. If that happens I will scream out loud and hopefully someone will listen.
I found the same thing over the years with the Windows versions. You couldn’t pay me enough to use Windows 10. Only version I use now is Win7 and that is minimal. I recently checked out my cousin’s Win10 laptop that was very slow. What a nightmare trying to get it working relatively normally again. The worst is the default automatic online stuff Windows now forces users to put up with. It’s difficult to disable it. It seems the common theme is, the newer the version starting with Win8, the less control of the OS the user has.