We have looked into expanding Bluetooth support in the GX at several points, but each time the conclusion is that Bluetooth is just not the right solution when it comes to charging.
It has its place, and it’s very nice for setting up systems, but when it comes to maintaining a super reliable connection you can set up and forget to support charging, it just isn’t the right thing.
We have the GlobalLink520 product that offers Bluetooth connection to Victron components, and then send the details on to VRM. And it’s working nicely, but it’s done on an optimistic basis, and missing some signals here and there is acceptable for that context.
We also have some support for Ruuvi and other sensors, but they are purely for environmental monitoring, not battery charging control.
I don’t expect this situation to change soon.
The smart battery sense in combination with an MPPT, can work well, but then there is a special relationship using a voltage offset, combined with the reliable local voltage readings on the MPPT to make it work well. It’s more complicated and “smart” than one might think, and a specific solution for when there isn’t a hardwired GX.