You cannot sign a pre contract with a club that competes in the same league because there could be a conflict of interest when you play. You can agree to sign a contract through intermediaries but cannot actually sign it.
I now have a question for you.
Do you not find your club incredibly frustrating? They have all this power in the Bundesliga but they are destroying it, I worry about City's dominance but you have done that for 11 years. On top of this I do not get why you hired Tuchel. I think this was a mistake and you will come to regret it just because he is too much of a practical manager.
I think you can, but I'm not sure. All the reporters said Bayern had signed Laimer on a free in January 2023. They didn't officially announce it though. They only did so in summer, with photos of Laimer wearing winter clothes signing the contract and with the Bayern directors (who had since been sacked) very clearly cropped out of the photos. So I'm not really sure if there are loopholes or whatnot.
As for whether I find my club frustrating and accused of destroying the Bundesliga, I cannot understand this. Let's take a hypothetical scenario where for whatever reason Bayern decide to stop existing. Do you honestly think that the Bundesliga would get better? Can you imagine how a Bayern-less Bundesliga would fare? I mean, just imagine the next time the TV deal is up for renewal. I think Bayern is actually the only reason why the Bundesliga is still relevant. Do not listen to what other fans of German clubs are saying: they sometimes say stuff not because it's true, but are conditioned by jealousy and hate, and I don't blame them because I'd also probably hate Bayern if I supported another German club.
As for Tuchel, I still don't get why we sacked Nagelsmann very late in the season at a time where had we won all our remaining matches we would have 100% mathematically won the quadruple.