The "lora.join(...)" can be avoided after the first time by using "lora.nvram_restore()" (after creating the "lora" object) and "lora.nvram_save()" after sending the LoRaWan packet.
The LoRaWan counters are preserved.

To specify the battery, you need to know how many days battery shoud last, the operation duty cycle (time awake / (time awake + time sleeping), the power consumption in each cycle.

Are you going to use LoPy4 alone or with another board like Expansion Board v2/v3.0/v3.1, or PyTrack, or PySense, etc ? LoPy4 current in deep sleep is about 20 uA when alone, hundreds of uA with Expansion Board.

If WiFi and Bluetooth are not needed, just disable them :

• pycom.wifi_on_boot();
• bluetooth.deinit().

Even the presence or not, and type of microSD card in Expansion Board/etc, changes the power consumption :
MicroSD power consumption on Expansion Board, PyTrack, PySense, etc.

Search for deep sleep in this forum to have more details.

Battery should last for at least 2 years.

Let's say your LoPy 4 stays awake for 10 seconds (that's a bit long already) and draws 200 mA average (that's quite a lot) during those 10 seconds, and 30 µA the rest of the time.

Then you draw an average of (10 * 200 + (86400-10)* 0.03) / 86400 = 0.053 mA (53 µA).

With a 2500 mAh battery, than means over 5 years in ideal conditions.

But remember to keep your active time as limited as possible. If you suddenly decide you want to wake up every hour instead of every day for instance, you suddenly jump to 585 µA average, over 10 times more, and your battery life drops to less than 6 months.

Don't forget to actually measure how much power your device draws in real conditions (running on battery, with all the sensors, no USB...), how long you stay awake, etc. The difference between theory and reality can cause big surprises!

If you have other questions, feel free to ask them in the forum. If you need dedicated help, I’m pretty sure there are people available to do that for a fee :-) (not me at this time).