Yes clearly a local communication system would be better for everyone, whether it uses Wi-Fi or BT, in fact for me the connection preference with a storage system as I said is always physical (direct) and not dependent on an external system.
With a REST system I tried to consider what the customers’ wishes are with the absolute application possibilities of the moment.
Because creating the possibility for all Bluetti devices to be able to communicate locally via Wi-Fi or BT for a local isolated connection with Home Assistant actually means updating all the firmware currently present on all devices.
While creating an extension on an existing cloud to access the data already available, without the need to modify any firmware, could be a faster and more feasible way in the current state to obtain the need.
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It’s a bit like the philosophy of seeking a balance between the request and the concrete possibilities of the other party in order to more easily obtain what is requested.
This is because we are talking about something that must be compatible with devices already on the market, a retroactive change therefore.
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Another idea, thinking of a system that acts as a BT connection with Home Assistant, could be a BT gateway that on one side connects with the Bluetti device and on the other allows it to act as an MQTT endpoint.
For example, currently the Bluetti App has MODBUS support for all Bluetti devices equipped with a BT interface and therefore has an internal DB that allows the transmission and reception of packets in compatibility with these devices.
Along the lines of this, it could be possible to create a device compatible with all BT Bluetti devices that allows integration with Home Assistant.
As an example a custom display running Android with a customized Bluetti App that will serve as a visual gateway of the connected devices, showing devices and statuses and running local listening services. 
Hi, I´m running an EP600. Like many others, I´m currently using the “unofficial” bluetooth connection (via a raspberry pi) to read the current power values (PV in, total consumption, etc.) and SoC for logging and display(via Node Red). I would very much appreciate some kind of interface to read this data directly off the network, so I can eliminate the somewhat quirky bluetooth connection from my system. Simple is always better :) For me pretty much any interface would do: mqtt, modbus over TCP, a REST API, I think I can adapt pretty much to anything as long as we have some documentation. I´m fine with just receiving values, writing could be left to the official app.
@Selfmadestrom Erik, thanks for taking the initiative! Would be great if we can get something moving :)
PS: fetching values from the cloud connection would be fine for me too!
Thanks for your input @tscher ! At the moment, i try to get into the github project to add units myself and make this an more active project!