That sounds great, maybe the Homey source code I posted yesterday can be used, just with adjustments for HomeAssistant.
I experimented a bit yesterday and managed to create a connection between HA and Homey. I can see the data from the Smart but I can't transfer it to ABRP. If I read the battery SOC from my VW Tiguan Hybrid and act in ABRP as if it were the Smart, then the data from HA is sent to ABRP via Homey and updated every 5 minutes. Perhaps that will help when programming the app for HA.