The lastest binaries are entitled tasmota.bin version 8.1.0. Once it's flashed the shelly will create a new wifi access point on ssid "shelly-xxxx", you'll need to connect to that wifi to configure your house wifi/password in tasmota of the shelly.
Personally, I flashed some initial shelly devices with tasmota (which is absolutely brilliant) but then stopped once shelly supported mqtt and provided continuous software updates with new interesting features (eg DDD actions). Through mqtt my shellies are made accessible to homebridge, so I benefit of both "worlds". Activating mqtt deactivates some shelly cloud features but I don't use it, I use the Apple home app for remote access to homebridge.
I don't think the flashing process is reversible ie replace tasmota by shelly binaries, which is another reason why I left shelly firmware.