I have a Pro 2 too and switched from Xinput to Dinput at the back of the controller and my Steam Deck now identifies the back buttons like L4/R4 (but with the name PL/PR) and I can map it to anything I want

If you don’t have a budget to upgrade to a better laptop anytime soon, I recommend using a low ram distro, like Lubuntu and search for the best driver compatible for your GT 730. I believe this GPU barely supports Vulkan so demanding 3D games will mostly not run properly. You’ll have to stick with old AAA or indie games. Also, if using a Ubuntu-based distro, make sure the package nvidia-prime is installed to use your nvidia GPU instead of the Intel HD Graphics which are even worse. Good luck!

A friend once ordered a box of 50 to share with students from university and they delivered to the other side of the world not even charging shipping!