Hi @macthieu !
Welcome to Gladys 
Unfortunately, I have the impression that recently Tuya changed something in its API and the tutorial as provided in the docs no longer allows retrieving Tuya devices into Gladys… you’re not the only one to make that remark.
I investigated this topic a lot this summer without success.
In general, I broadly advise against Tuya devices — you route your data through the Chinese cloud and you’re at the mercy of their API. It’s fine for testing, but in the long term it’s not viable; your home is at the mercy of a Chinese API outage, it’s too unstable.
I recommend using devices that work locally and with an open protocol, so you’re not dependent on internet outages or the brand’s API being shut down.
My protocol of choice is Zigbee — in my home my entire place is equipped with Zigbee bulbs, most coming from IKEA (€9.99 each for a Zigbee smart bulb)