I wanted to run a diagnostic on my Triumph and ended up getting another diagnostic device thing. In searching for the 'best' I came across a thing called a Navigator TXbe made by Texa. I'd never heard of this before but it covers just about every bike with an ECU and diagnostic connector. This includes most BMW's and our beloved Ks. It also comes with a load of technical information including wiring diagrams (turns out that's where K1300S diagrams someone sent me that I posted a while back came from). When viewed in the app, the wiring diagrams are interactive, and give you a picture of the component and location on the bike.
Functionally it seems on par with a GS-911. It has a couple of things I don't remember seeing in the GS-911 (e.g. ambient light level), it can reset the clock and service reminder and doesn't have a VIN limit or anything like that. It can add TPMS sensors, but I don't think it can change the display to Psi like the GS-911 can.
Cost wise it's a little eyewatering at roughly twice the price of the pro version of a GS-911 WiFi, though it does cover almost all bikes (currently over 7000) not just BMWs. They do come up on eBay occasionally but the software is protected using a HASP dongle and without that it's useless. Happy to help with diagnostics/service resets/info etc. if it's of use to anyone.