I am currently also dealing with the topic. The reviews of the BurgWächter devices online are somehow not so great. On YouTube, there is a video from a specialist dealer about long-term experiences with use in a fire station. That at least puts it into perspective somewhat. If I remember correctly, the specialist dealer no longer sells the product either, maybe too many complaints after all.
I am currently leaning towards an Ekey fingerprint scanner in a video intercom system, but I am still missing the suitable counterpart as a lock. I don’t want Nuki because of the noise. Ekey itself offers a CES lock cylinder with a radio module on the website. Apparently, however, this is one that is not suitable for doors with core pull protection. That one is only available through the specialist dealer. After longer research, I also came across ELOCK2 and Simons Voss radio relays, but also only through specialist dealers. Of course, all of this is significantly more expensive than the BurgWächter devices.