I have been planning to install a smart lock on my front door for a while and recently made some steps towards picking what I wanted. I didn't really want the hassle of switching out the current lock and went for a retrofit option.

From my very limited knowledge, it looks like I have a EU Mortise lock (see pictures) and settled on the Aqara U200 (https://www.aqara.com/en/product/smart-lock-u200/) which I was going to get from Australia. 

However, for the retrofit to work (without replacing the lock mechanism) the knob on the inside needs to be removed, but I can't figure out how to do that. I have removed all the base plates (see pictures) but I still cannot remove the knob and I suspect it might not be removeable. 

Does anyone have insight on how I could do it?

Failing that, I will have to consider do a more intensive replacement. If I have to do that, are there any recommendations? I am mainly Google Home based (although my wife is an iPhone user). I am planning on moving to Home Assistant at some point soon. Main features would have to be being able to use finger print, give temporary access keys/codes and being able to control it with my phone.