You’re definitely right on this. I posted about this here
Although the suggestion to use the tplink device tracker configuration works fine on other TP link routers, it won’t work for the M9 - I’ve tried without success.
Currently I’m using wifi connection to the M9 for location tracking for relatives that come over to override automations where I don’t want to install the smartapp on their phones, but I have to use IFTTT, which really is terrible considering this relies on the cloud instead of going through my house where the device is located in. I can’t believe there isn’t a local solution. I like the M9 as a router and the performance and range are great, but I would never buy a router again that relies on a smart app to configure it. The UI in the deco app is garbage and not only is it impossible to configure things that are simple on other routers, If TPLINK pulls their app or cloud service down, I have a glorified brick in my house.
Short of installing the Home Assistant App, other options include Monitor bluetooth tracking - but you have to obtain additional RPI’s and hardware to run it on. Creating an entitiy by pinging the phone’s IP might work if its not an Iphone (they go to a deep sleep). If Iphone, there is some sort of IOS integration through the Icloud I believe (not too familiar with it).
If IOS, someone on the other thread mentioned this Iphone detect option as well