I think upgrading the RAM as you mentioned is going to make a big difference. While the physical RAM might be soldered to the motherboard, you could buy a fairly cheap SD card or USB and set the system up to use that as virtual memory. It won’t be as fast as actual RAM but it might help and large SD cards are honestly really cheap these days.
An investigation from a neutral third party is a good thing, but in this case LTT hired the third party investigator so the investigators obviously have an incentive to find LTT innocent of all charges since LTT is paying them through Linus Media Group (LMG). It’s better than nothing, but it’s like when there’s an internal affairs investigation into police misconduct… by the police… Nobody believes it and for good reason.