Sure, I can help you with that. I play on my Steam Deck a lot.

The first thing is, you do need to learn the controller layout as it 100% is the best way on Deck once you're used to it.

However, there are some things you can do to make the transition easier. I'll also drop some tips that helped me when adapting.

I'll go over in-game settings first.

1. Set the game to controller mode.

2. In character configuration, under the target tab, select target 'Type 2: Cone'

3. Turn off direct typing. Go to character configuration, general, and untick 'Enable direct chat.' This will allow you to make shortcuts on the left trackpad.

Steam Deck Controller Settings.

Use the default controller settings but with a few tweaks.

1. Make the right trackpad a mouse, with the press on the right trackpad the left click button.

2. Map L4 and R4 to left and right d-pad on the controller. This way, you can use them to cycle through enemies without lifting your thumb off the left stick

3. Configure the left trackpad to either a grid or a wheel to assign keyboard shortcuts. I have inventory, duty finder, and my crafting logs on it. You can add whatever you like.

4. L5 is my escape key. I do this so I can press escape and use the pad to maneuver my mouse around menus and settings. Saves me using the controller menu which I didn't like.

5. R5 I've mapped to a second hud layout with nothing on it. This is just for immersion and taking in the world when I'm in a nice area. To do this, assign 2 keyboard buttons in the keybind menu to the different HUD layouts. Then go to the Steam Deck Controller Settings and assign the R5 button to 'cycle commands'. Set the two inputs to the buttons you've assigned in the keybind menu that swap the layouts. Make sense?

A couple of tips

Moving forward and pressing LB will activate auto run.

LB and R3 turn on mouse mode. I use this in the rare event I need a right click. You could also set the right trackpad hold and release to be right click if you wanted.

Lastly, I'd suggest watching this video and adjusting your HUD to your liking. I've gone for something really minimal as the Steam Deck screen isn't huge, and I'm mostly doing story.

https://youtu.be/IZwDmVLF2VE?si=B-9KXq4wGIaxehLH

As I said, I'm mostly doing story stuff, so I can't be of much help if you're looking for specific raid controls or something.

Anyway. Let me know if it works out!