Tasmota VS zigbee2mqtt

BTW, there is one more way - if your devices are connecting to some kind of central hub, e.g. MQTT broker, they may send a "sticky" (retained) message with discovery info to some known topic - Tasmota is using this way, devices are publishing to tasmota/discovery/id and every time MQTT client connects it gets lastly updated autoconf info.

Just seeing your edit. WeightRaw is changing, so that is a good sign that everything might be hooked up right. I believe weight is in KG so it won't necessary change unless you put over a KG on the scale. I looked at the code for this and couldn't easily figure out what might be causing the calibration failure. I don't have time to figure out what all is going on there.

These are Tuya ones (unfortunately, the specific one on Amazon has been removed now, so can't share a link) reflashed with Tasmota so I can use them natively with Home Assistant rather than bouncing through a third-party cloud service. Bit of logic to manage the transitions from "not using power" to "using power" and convert that into notifications to the various Google Homes.

If it's a simple thing, the Tasmota firmware might do everything you need without a single line of code.

The lesson here is to never buy a smart home product which can only be controlled/montitored/upgraded via a cloud service provided by the hardware vendor. If the product cannot be controlled and monitored from your home network while unplugged from the internet, then there is some risk that this type of experience can happen again. Tasmota [0] allows a user to erase the vendor provided firmware, of ESP chipset devices, with well maintained open source firmware so that is never reliant on the vendor ever again. This is one example. Perhaps there are others.

[0] https://tasmota.github.io/docs/

You can use wifi devices, you just have to be careful about it. Anything that is supported by the Tasmota Project (https://tasmota.github.io/docs/) can be re-flashed with their firmware which doesn't make any calls to the internet and will directly talked to by anything that supports the MQTT protocol (Home Assistant, Hubitat, etc)

Here's the list https://github.com/arendst/Tasmota/blob/development/BUILDS.md

Fortunately there are lots of good options. Take a look at Zigbee2MQTT (what I would recommend for integrating Zigbee devices with Home Assistant) and the supported adapters list.

One planned change in particular might be the cause of some redos: I’m going to be switching from ZHA (Zigbee Home Automation) to Zigbee2MQTT (z2m). Though I’ve used both before, I didn’t discover z2m until after I’d set everything up at home. I like it a lot more and think I’ll put it to use as part of the redo.

Regarding question 1: tuya are well known to implement custom commands in their devices in an apparent effort to stop them working with 3rd party hubs. You only have to look at issues logged for tuya on the herdsman github (open source zigbee stack) One example: https://github.com/Koenkk/zigbee2mqtt/issues/9057 where older versions of the device worked in a standard way and then they changed it. Open source community keeps reverse engineering it like there but typically 3rd party commercial companies wouldn't do that so it would likely not work (properly). Comment from a tuya engineer when one of the guys on that issue asked them for help:

I'm using the Texas instruments CC1352 as controller on Home assistant for about 2 years now and it's working great. On www.zigbee2mqtt.io you can find some drvices which can act as controller.

I personally use Home Assistant on a Raspberry PI 3 (moving to a 4 soon) myself, along with a Conbee II (a USB Zigbee radio) that's hooked up to Zigbee2MQTT, which can connect to Homekit using the Homebridge homebridge-z2m plugin. Home Assistant is great but does require a fair amount of setup. I also could not use the Zooz sensors in my setup unless I bought a Z-Wave radio and then did some additional setup - e.g., following this guide. Compared to other options, Home Assistant has a ton of flexibility. I use Node-Red to write my automations but it also has skills and Feel free to ask me questions about it if you want to learn more - and check out r/homeassistant as well. You don't have to get a Raspberry PI for Home Assistant, either - you could run it on your home PC or buy something like Home Assistant Yellow to run it (though there's quite a bit of lead time on Yellow).

I've been using Zigbee2MQTT for a couple of years now and I'm still loving it. I actually also wrote a plugin, homebridge-z2m, to make it easy to connect it to Homebridge.