A bit too old now.
While I love the GUI, the file system (typed files, applications as folders, uniform display and print graphics, and a modular file system) the font manager and the standard applications (especially Draw), I haven't used RISC OS in over a decade. It lacks a lot of things that are needed for modern desktop/laptop use: Multi-core, pre-emptive multitasking, proper UNICODE support (unless this has been added since last I looked), support for most USB-devices, support for graphics cards, and so on. It is also a problem that it is written in ARM32-assembler. Not only does it make it harder to maintain, it also limits use on ARM64 and other modern systems (except through emulation).
I think the best route would be to build a RISC OS desktop on top of a Linux kernel, rewriting the RISC OS modules and applications in Rust (or C), and use Linux drivers etc. to make it exploit modern hardware.