The Interim Computer Museum (ICM) and SDF.org have made 28 vintage computer systems accessible online for free. There’s a plethora of old but gold - some legendary - systems available, so your visit should be like entering a living museum of computing.
All you have to do is point your browser at connect.sdf.org and login by typing ‘menu’ to gain guest access to the systems. Typing ‘1’ toggles between pages, revealing the full 28 choices.
BeOS is my favorite desktop OS of all time. Nowadays I run Linux on all my machines, but there are things that it was better and faster at on a Pentium 75 with 16MB of RAM than today’s multi GHz and multi GB systems running Linux, MacOS or Windows. I’m not sure how much of that you will see in a demo like this, as is was more day to day things from back when we cared about local files and applications and weren’t permanently connected to the internet. But still, it was amazing.
BeOS was pretty neat. It’s almost a shame that it was a proprietary dead end.
The https://en.wikipedia.org/wiki/BeBox was also quite an impressive thing on paper in its day though you kind of knew it was going to be unobtainable and/or too expensive.
Haiku has come a long way, I’m told, but I haven’t tried it yet (and I don’t think I own anything that can run it on bare metal)