while browsing the internet for new presence detection ideas, i found these service from Linksys:
https://www.linksys.com/us/linksys-aware/ for there Velop Mesh Routers.
Its based on this technology: https://www.originwirelessai.com/ they are using wifi signals to detect motion
because signals are affected by a person.
For now Linksys offers no API or integration but they think about it!
I will write Linksys support that a integration in other devices or services will affect me in maybe buying these mesh system. If someone else is interested in this technology, consider to write too.