So while reading up on AFDD’s to avoid being annoying on this forum I came across Self-Testing & End-Of-Life RCD’s... seems like a handy invention that would be of interest:
https://www.westernautomation.com/solution-centre/electrical-protection-technology/self-testing-rcd/
Searching “STEOL RCD” reveals a few patents but little else so I guess I can’t pop down the shops to get one!
