@brentfamily51, I have been making my own sensors. Lately I am looking at getting Bluetooth devices connected to our hubs.
My goal is to make Bluetooth gateway for our hubs. Bluetooth is a good standard. However, it is very flexible one. Each devices can implement some part of the specification not others. The flexibility also introduce complexity.
For the devices that I own and tested, a couple of them use Bluetooth advertisement. It is very simple to collect the advertisement data. The device will send standardized Bluetooth Advertising packet.
I am also able to control some Devices as well with other aspect of Bluetooth protocol.
If you can dig a bit on how those devices that you want to monitor use Bluetooth as protocol, perhaps you are lucky that the data you want to monitor is in the advertising packet.
Android has Bluetooth packet sniffing log that you can enable and download. This data can be uploaded to Wireshark. I used this to learn about my bed many years ago. Today, the android sniffing steps may be different. You may need to google them. If you can get data from the sniffer, you can learn a lot to move forward on your goal. You can find out whether pairing is needed. You can find out whether it is encrypted.
The above assume that you cannot ask the maker how they use the Bluetooth. Some maker is happy to tell you what you need to do to connect to their devices.
