But I just don't think Oracle were able to sell it – and Oracle's sales people are really good, if they can't sell your product, the problem is likely the product or market fit not their sales ability
RiscOS simply had to start the whole OS cycle from scratch, it wasn't as good as what was already available on the Amiga and it wasn't Unix. It was fun to work with if you came from the BBC Micro it all made good sense and was a step up. But when looking at it from a corporate angle it wasn't quite what you'd expect from a workstation and it didn't run anything that you needed right there.
Did Oracle port any applications to it?
JavaOS was in ROM, on a module that can be removed (SIMM-style form factor). At one point people started to use BOOTP to run Linux compiled for SPARC as a replacement, as JavaOS was unpleasantly slow on JavaStation hardware.
So Sun Network Computers were JavaOS on SPARC, Oracle were NCOS (Acorn RiscOS derivative) on ARM – and I think IBM's had a similar tech stack to Oracle's...
were there any others?
IBM Network Station used PPC
And although its OS was called “NCOS”, it was completely different from Oracle’s NCOS. It was apparently a closed source derivative of NetBSD