Whenever I play games, I can't possibly click both buttons at the same

They came out with a software update that fixes this issue. Go to Settings, About Device, System Updates. Once you load the latest update it allows you to use multi-touch features like zooming maps or playing games.

I had the same issues but what I've figured out while setting PPSSPP emulator and it worked for me:

First, make sure to use the Vulkan, it has been added recently, and it works amazingly:

For average hardware smartphone, Buffer Rendering works good. Otherwise, select the "Non Buffer rendering"

Then, enable all the Performance hacks under this menu expect, "Retain Changed texture"

Then setup controls according to your needs.

Moving next, under the System->Emulation, make sure to use Change emulated PSP's CPU clock (unstable), use the maximum available value available. This will boost the performance on many games.

For rest of the settings, you can try yourself or following the below guide:

https://techshali.com/best-setting-ppssp...

Hopping for better results!