Since there is no proper answer to both questions, I'm opening a topic with the proper instructions. Attaching screenshots with the end result.

- How to run the game in 1920x1080 (the UI is a bit stretched, but everything else is rendered properly):

Edit: C:\Program Files (x86)\GOG Galaxy\Games\Shadowgrounds\Config\options.txt

edited part:
screen_height = 1080
screen_width = 1920

- Change camera angle to something more comfortable. Also disable camera shortcuts in the OPTIONS menu, or it will reset with no other way to fix than restarting the game:

Open with 7zip: C:\Program Files (x86)\GOG Galaxy\Games\Shadowgrounds\Data1.fbz
Edit: Data\Misc\default_game_options.txt

edited part:
camera_max_beta_angle=50 (original is 60)
camera_min_beta_angle=20 (original is 60)

change if you like:
game_flashlight_energy_usage=10 (if 0, the flashlight will not consume battery)

For "Shadowgrounds:Survivor":

- Change camera angle to something more comfortable:

Open with 7zip:
C:\Program Files (x86)\GOG Galaxy\Games\Shadowgrounds Survivor\Data1.fbz
Data\Misc\default_game_options.txt

edited part:
camera_min_beta_angle = 20
camera_max_beta_angle = 35
camera_default_beta_angle = 35 <- this is the one that actually has effect, didn't bother to change the others again

- Fix the water rendering bug (in Sewers level and later):

While in-game:
Press F8 to bring down the console and enter /render_distortion 0


In the launcher:
Disable "Distortion Effects"
OR
Disable anti-aliasing

Very cool! Looking forward to testing this out soon on my first playthrough. Thanks!

Any chance you could figure out how to do this w the Alien Breed Trilogy?

There was an FOV Tool someone created for each game at one point (listed on PCGW), but it seems they have vanished from the web. A bit less zoom and better angling would do the series some justice, I think. (Though I've only just started Impact)

An year too late - sorry! For some reason the forum doesn't properly display alerts for me.

Yes, there was an option to change FOV for the Alien Breed games, and No, it was very buggy. Every time the game shifted to scripted angle camera it would mess everything up. The first game was barely working with it, but the second one was unplayable. I finally gave up on it, and used the regular camera.

But I really didn't like the Alien Breed games. Forced myself to finish them, but it was a chore. The best thing about them were the comics between levels.. :D