Got offered to resign my job, what to do??

After working 3 years for my company here in Munich, last week (Thursday) I joined a random meeting where HR was involved, and they provided me 2 options going forward and gave me a 5 working days deadline to decide;

1 - Leave my company - A mutual agreement where they would offer me a "bonus", which is summed up around 4,5 times my brutto salary, additionally they mentioned they would still pay me my regular salary for the upcoming 3 months (this is not present in the document sent to me though).

2 - I join PIP (Personal Improvement Plan) for the next 3 months, where they will measure my performance on a variety of things (some that make no sense and does not solely rely on me to provide the final outcome).
By the end of PIP, I have the chance to appeal the decision or to leave, if I leave, they offer me an additional 1 month salary*

*In the offer they clearly state "If you choose to leave".
** If I decide to appeal and the new analysis also comes as unsuccessful, they once again state "you may choose to leave", which I would be entitle to 0,5 my monthly salary.

In the final part of the document, they state that if I decide to go for the option 2, my manager can (not must) provide coaching, assistance and support for me to achieve these goals, however the responsibility of improvement and delivering results solely relies on me.

***They also state that the PIP could be lengthened or shortened, depending on the assessment of my manager on a weekly basis.

What would be the best options here? Is there a government body for this that could offer me advice?

Side notes:
1 - In the middle of next month I would have vested stocks available, which after being sold correspond to around 3,5 netto salaries. All the other shares that would be vested in future, are lost.
2 - I still haven't taken any holidays for this year, wouldn't they be require to mention this in the document or even account this into the final offer?