Haven't had a problem with it with both amd proc and GPU.

In fact, didn't have to do anything to get it working in Mint Linux, just installed from steam and it worked.

I can’t speak to all systems or configurations, but my desktop is Arch-based with the Nvidia 535 driver (a few versions old, I’m still waiting for the explicit sync driver support), I run the game through Xwayland (no gamescope), and I’ve been using protonge 9-2 as the compat tool. The game runs really smooth in my experience, and on protonge 9-2 I don’t have issues switching windows/workspaces.

I do run the game in exclusive fullscreen— I recall the window having a single white pixel border in borderless fullscreen.

I run it on my Steam Deck every now and again

You get medals and requisition points from playing that you can use to unlock new stratagems, which includes everything from weapons to orbital bombardment. Medals get you new weapons, cosmetics, etc. You also find samples you can collect on missions, and these unlock permanent upgrades for stratagems. There are player levels, but these just unlock new titles once you get past the basics.

The battle pass equivalent is Warbonds, which include new weapons, armor, cosmetics, etc. Unlike most games, warbonds don't expire and you can find enough premium currency while playing to get them without too much trouble.

On the whole, new warbond weapons tend to be different rather than obvious upgrades. The default assault rifle you get stays perfectly viable throughout the game.

The difference here is splitgate stuff was (afaik, only played a tiny bit) all cosmetic. The helldivers passes actually do have different weapons and armor so it does change how you play, but most weapons are viable, especially at lower difficulties so try out everything and see what you like. But again, absolutely no time limit on anything in the game except the super credit store (which is just extra armor and it rotates through a normal cycle) and the missions themselves.

Just some very general tips so you aren't too lost. Enemies can call for help. Bugs rear up and bard orange pheromones into the air. Bots shoot a flare. You can kill them before they finish calling for help. Some enemies have armor. If your shots bounce off, try hitting a different spot or use a gun with armor penetration. 380 barrage is useful for big enemy bases, but tell your teammates. It hits a BIG area. Difficulty only changes what enemies spawn and how many. No changes to health or damage.

Also even the earliest unlocks are usable at the highest levels, so don't worry about using "noob" stuff.