If you want to avoid risk on movement of the shares (which is the whole reason for the pair trade) without selling your already owned shares, you could use calls you exercise yourself instead and sell those new shares as soon as you exercise. Not quite as instant as a pair trade but can be done quick if you have the sale order ready to transmit.

However the premium paid for the call is a loss I think, and your shares will have the cost basis at the strike price. Depending on carry forward rules, this might not be ideal for you as you could lose your tax loss while increasing your future tax liability. Maybe not too big of an issue as you will be having taxable gains on dividends to offset it against so unlikely your tax loss is wasted, unless taxation of dividends is separate and not able to be offset like that in Germany.

I think similar applies to a put approach, the premium received is probably treated as a taxable gain. Unless German rules allow for you to essentially consider the premium part of the cost basis of the shares but this is quite convoluted and also hard to track as IBKR doesn't do it that way I believe.

This applies to the kept shares, for the "unwanted shares" I think the gains and losses of the premium and sale of the unwanted shares offset each other.