I wonder if companies that produce IoT aren't aware that if they make the access to their devices easy for tinkerers like me, this is free marketing / recommendation for them. I would never recommend devices with closed local access to anyone.

Deye's openness is so-so. It definitely could be improved. The local access is at least somehow possible, but not well documented and hacky.

https://blog.rozman.info/integrating-deye-ev-charger-to-home-assistant/