I guess it depends on how you define “major.” It’s possible to find one of those Thinkpads, but it takes a fair amount of research through conflicting or ambiguous info - there are a much larger number of Lenovo laptops that won’t work, and even the ones that do aren’t really 100% on the trackpad.
The right way to look at this, I think, is not “BeBox”, but “DayStar”. Back in the brief period when Apple opened up the Mac to clones, BeOS had also moved its PPC focus from the BeBox to Macs, and DayStar came out with a MP clone that shipped with BeOS 3 install media along with MacOS 8 or whatever it was then. And of course BeOS ran spectacularly well on it.
Sadly, a dead end path for Be, but it was great for them while it lasted. It just couldn’t go anywhere because of Apple and PPC. The issues for Haiku, if something like that could be set up with one of the small outfits that do their own laptops - Slimbook, System76, whatever - are more about whether it’s a good product and can be supported across model generations.