You already bought a TP-Link Kasa, so I’d just stick with those. No flashing necessary and you can deny them Internet access after setting them up.
Any generic switches you find on Amazon are most likely Tuya devices, but newer Tuyas cannot be flashed with Tasmota over WiFi. In my opinion, they’re not worth the trouble unless you enjoy taking them apart to flash Tasmota.
Kasa has 3-way switches, but I don’t know if they have 3-way dimmers.
In the Kasa app, you can set the dimmers to be Instant on/off or fade at three speeds.
As discussed in your other thread, HUE emultation doesn’t care what the device is. It just has to be an item type that works with HUE emulation.