I was unaware of the SSDP component of that project, but it seems to require having the Physical Web app installed. Their BTLE beacons work on Android devices without anything special installed on the client. Maybe the SSDP does work on stock android but just takes a bit? This doesn't work if the client has to have a specific app installed to receive it.

This is great, thx for the link. Been thinking about this for 10 years, nice to see someone being more proactive than just thinking about it!