It depends on what variant you have. A lot of android phones like LG will have a few part variances between models like the charge port and cameras. You’ll have to look at the model number on the back. It’ll start with LMG followed by a few numbers then one or two more letters. From what I’ve found one of the variants is shared by the G7 one, but again, it depends on your model. You can check Mobile Defenders, Mobile Sentrix, and Injured Gadgets for parts.
I know that are can get warm when it boots up. Whenever it comes to liquid damage you do want to inspect the entire board, including under those shields. I would just let it sit for about 10 minutes after boot up to see if that heat goes away. If it shuts off or stays hot, that’s when I would check under those shields.
While you did damage the phone, I don’t think it was damaged “for good” as 95% of the time your devices are repairable. I would send it to a board repair specialist like iPad Rehab or STS Telecom or Rossmann Repair Group. All of them specialize in board repairs for apple products and they all have youtube channels you can check out.
As long as there’s no underlying issues with the board, all you need is a new screen assembly. You can order a repair kit from ifixit with the tools and do the work yourself. Just be careful with the home button. You’ll need to transfer it in order to maintain the return to home and TouchID functions. A heat gun or good hair dryer will come in handy with transferring the home button and front camera assembly. Take your time and follow the guides and you’ll be golden. Also you will lose TrueTone unless you have the programmer to transfer the original screen’s serial number to the new screen. But none of my customers notice it’s gone when I replace the screen.