I really did not do much because the LiFePo4 batteries I have are all BT enabled, so I only had to make a BTE dongle with a ESP32 board I had laying around, then I got installed in HA and they were detected right away. Added the BLE BMS package found in HACS, paired the batteries to that package and voilà, I had all the info batteries BMS exposes via BT. Only problem with this is that the original app does not work anymore because the batteries only support a single BT connection, but when the boat is on the water away from home, the app works perfectly as before.
Before that, I used a Shelly UNO to monitor the battery voltages directly in HE, this did work good but knowing the voltages only was not very helpful when I switched to LiFePO4 batteries, then I stumbled on the BLE BMS package this winter and this seemed like the right way to go in this situation.