You have hands down the absolute best lighting I've seen in one of these types of videos. Great job man. Really, really appreciate the budget screen protector but still the quality of such a simple type of video.
Good tip for installation. Go into your bathroom. Turn on the hot water until moisture starts to condensate in the room. This will cut down on particles in the air. Proceed to clean the screen and apply the protector. It's helped me install all of my protectors without any small dust/dirt accidentally adhering to the screen.
The bubbles exist due to particles on the screen phone. Use scotch tape and go over the phone with it vertically to remove any fine small nicks of dust. Use a flash light or bright source of light to ensure that you have gotteneverythingg then apply the tempered glass.
I'm not team no case but I have in the past just used a skin on my phone and it was awesome. I actually thought about doing this with the Pixel Fold and using a leather skin with it.