The firmware you have used is the tasmota lite version and is earlier than 9.2.0. That is the reason why the integration has not picked up the device. You need to upgrade the device to tasmota full version and above 9.2.0 release. If you need any help with upgradation please ask.
I used this guide, in which they asked for upgrade from the web interface, which I did. I still have to upload tasmota.bin?
Btw after plugging it back to the power circuit, it is unavailable. After factory reset (six plugins), I can open the lite interface but adding my wifi network makes it unavailable again. It seems to me to be still quite unmature in comparison to Shelly, which otherwise have many other problems.
v1.0.11 v3.9.22 v4.2.0 v5.14.0 v6.7.1 v7.2.0 v8.5.1 v9.1 Current release
I encountered the same issue you did and then followed the recommended upgrade path. The only difference from what you did is that it’s unnecessary to upgrade to the minimal version before the full version (I upgraded from one full version to the next full version).