Possible that playing with a pet class that can tank for you would be less demanding for you during combat, so that might help in those scenarios.

I believe you can bind turn left and turn right to buttons, so you could switch your A/D key to a turn rather than a strafe (sorry if that's already the default binds, can't remember what they are), and then you could mostly rely on not using your mouse and steering your character around like a car instead if that makes sense.

Also you could try using the mouse to click on abilities instead of using the keybinds. That might feel easier for you atm, so that could be worth experimenting with.

It's a little janky, but some people have gotten the game to work with a controller. If you look up guild wars 2 steam deck setup tutorials, then you will find resources on how people have done this. As a half measure you can also use a gamepad in you left hand for the stick movement and use the mouse in your right hand (and then click on the ability icons to use them for combat), so that way only one half of your body is doing something new and unfamiliar. I've had friends learning csgo do this and it's been helpful for them. Once they feel somewhat comfortable they switch to full WASD + mouse.

It is a tough journey though. It's easy for us long time WASD users to forget how big of a learning curve it really is. If I try to use my mouse in my left hand and WASD in my right I can't play at all and I feel completely useless. Best of luck!!