It's also serviceable as a very cheap 'full PC' option, although I do think a better option in many cases would be a second-hand laptop and therefore getting a screen, webcam, trackpad, speakers, headphone socket and slightly bigger keyboard in one unit, even if that comes with an old battery. It depends what other equipment you might be able to reuse or scavenge, and how fixed the budget is you're working to. If you're using a Pi like this a headphone socket can probably be provided by a cheap USB sound card (two or three quid from a UK seller on eBay) and would really be necessary where people are sharing limited space.
Hobbyists may be interested to know the RasPi can also natively run RISC OS, although for compatibility with 80s/90s apps, games, etc VirtualA5000 (see riscos.com) may suit retro fans better. Or it may be possible to run ArcEm under this version of RISC OS directly, which would be a neat recursion.
It can also run other operating systems: https://www.youtube.com/watch?v=1jrVyFEvYT0
Even with renewed interest it's still surprising for an Acorn-based OS to be running on a new all-in-one computer. The balancing act RISC OS Open have got, apart from finite resource, is how much the OS can ever be modernised and still be regarded as RISC OS, when you can heavily customise Linux desktop environments on (or even build new ones) to far more purpose. But whilst it may be a curio you can now carry a complete Archimedes A30xx style machine in your pocket, plug in a TV and mouse and bask in what The Meaning of Liff calls Aberystwyth.
People have posted comparison pics with the BBC Micro and original rubber keyed Spectrum. The Pi is much smaller than the BBC Micro but a bit larger than the tiny Speccy, even without a keyboard keypad:
More info on Pi 4 compatibility at https://www.riscosopen.org/news/articles/2020/10/24/risc-os-5-28-now-available and https://www.wrocc.org.uk/risc-os/a-guide-to-risc-os-hardware is a more comprehensive round-up of RISC OS as it is now. RPCemu now has some bundles http://www.marutan.net/rpcemu/easystart.html to help you check out RISC OS 3.71 and other versions. Note that the version numbers and which company or group produces what are a bit of a mess. Versions 4 and 6 were developed by the now-defunct RISC OS Ltd and are available via riscos.com and virtualacorn.co.uk (mainly for emulation). They've even got a classic ROMs collection that includes RISC OS 2 and Arthur OS.
Switching tack completely, earlier in the year I happened upon http://archivemag.co.uk/Volume24/06/ via @Cheekyshot1 who retweeted something in response to a response to a "how long have you been programming?" tweet. It got me slightly regretting having pitched (as far as I know, there may still be some in a loft) all of the old Acorn discs I had, along with the A3000, A3020 and latterly an A5000 acquired from someone else's chuck out. Particularly ones with software I'd written on them (two spring to mind, a flat file address database and an application to auto-type school report statements filling in names and pronouns). It'd be functionally fairly useless these days, there's not much call to do DTP with Impression or Ovation, but it'd be interesting to look back on. As I recall the tricky bit was to populate a list with a variable number of entries.
I'm still probably not getting a Pi to put RISC OS on, but it's nice to know there's steam behind doing so.