The idea is that leaving the country is taxed as if you sold your shares.

So selling them presumably doesn't help.

The idea is presumably that you would "sell" at an artificially low price.

Which is illegal if you do it for tax evasion.

and legal if you’re just helping your buddy out

Not sure if the tax office agrees.

Your taxes should work out the same (or worse). Exit tax is akin to you selling all your properties at the point of exit.

Yup, this is possible. It would have to be at some fair market value, and you'd (obviously) have to tax that in Germany. And depending on how much you trust your buddy, you might or might not have to draft up some complicated legal framework that you indeed have the right to buy back your company at some stage :)

Nothing. But you will have to pay taxes on the money you get from your buddy. If he is paying too little, you may get into additional trouble.