With a PIP you have a 15% chance of surviving at QCOM; a general statistic in the industry. Legal action against a lawyer ridden behemoth is financial s---c-de. A hard fact to accept is that you are hated by someone with power - this ain't changin'.
I'm an old engineer... I think I have seen everything... some advise that I would give to my son in your situation:
1) quickly accept your pending fate, your current career trajectory at QCOM has been set
2) with resume in hand, go to a technical temp agency and grab any job as a temp/contractor as a placeholder. Cashflow is more important than pride.
3) start looking for a new permanent position and don't be too choosy. A huge percentage of people hate their jobs .... but they have cashflow.
Most engineering jobs today are with sweatshops, salaries are not so great and there is no security to speak of. The amount of BS I read on this board is astonishing.... especially from people that left Qualcomm and claim they have discovered Nirvana.
All companies these days are under significant pressure to cut costs and deliver quickly. You are competing with guys that work 10+ hours/day and weekends because they are on visas.
"Sharing what you do on weekends" with co-workers.....
Let me translate for you: "you are supposed to be in the lab on the weekend you id--t!"
A final word.
When you find a different position elsewhere, work hard (10+ hours/day) , kiss a-- and always be positive KNOWING you can be fired at any moment.
Live well below your means and save your money, invest in assets that generate some revenue.
An engineering career is like walking through the 10 levels of hell - not so bad at first but as you remain in the industry it gets harder and harder. You will sacrifice your life for money.
If you work hard, s--- up (a soul killing experience) and save your money you will be in great financial shape when you are 50+ years old and can afford to get fired. If you don't do this, you may find yourself working at the Mobil gas station selling coffee, or at O'Reilly Autoparts selling oil - I have seen this first hand... engineers taking any job after blowing through savings because they refused to take any (engineering) job because of pride. Eventually they settle for any job that puts food on the table.
Thought this was some good advice by @XVYTOvE-3vsz