Nurse manager here. I'm really confused why you would need to lie? Especially if the PIP is "unenforceable".
If you want to quit bedside just do it. Theres so many other fields of nursing out there. Honestly and genuinely speaking, you sound miserable :(
P.S. Peds pts may be compliant but overbearing parents with unrealistic expectations or peds deaths are not fun to deal with. Its not all rainbows... I would never touch nicu, PEDs, picu for that reason
Also, yes, the Union rep that said you can get fired is wrong. Its super super super hard to fire people under Union. Even nurses that dont do their nursing interventions or watch Netflix day. Its truly wild what some Union nurses get away with. Pros and cons....