Is it possible to prefer external financing (retrospectively) over equity?

You always have to do that for disbursed amounts.

I don't know what the conditions are now, but for me in 2013/2014 the commitment interest rate was also higher than the loan interest rate.
I then also drew the KFW loan first because I had the largest interest rate differential to the commitment interest rate there.
Except for advance payments, the bank would be quite stupid to agree to a request for early disbursement if it is regulated differently in the contract.

I only know it like this: the installments only start flowing once a loan has been fully drawn.

It depends on the contract. In our case, a fixed repayment start was agreed upon and the first regular installments had already been paid, even though for various reasons only the shell was standing at the time and we had paid most of it from equity until then. Until the last drawdown, it was almost another three quarters of a year.

You do not pay a penalty interest, but a commitment interest. This reflects the refinancing/liquidity costs/equity backing etc. of the bank.

How can it be that the commitment interest is then higher than the agreed nominal interest rate? I mean: does the bank also pay more interest for providing money than when it actually disburses the money? And couldn't the bank then – like the borrower – simply "draw everything at once"? Or are there laws that prohibit them from doing so?

As far as I know, the commitment interest rate has been the same for most banks since forever. For my financing in 2018 and one I know from 2006, it was exactly 3.0% (different banks). Only the loan interest rates were significantly higher in 2006 and lower in 2018. This is not an answer to the question why... just the impression that this number simply was not adjusted. However, I have occasionally seen offers with, for example, 1.8% commitment interest in the meantime.

By the way, in my case, interest on drawn amounts was due on a daily basis and repayment started one month after full disbursement. And from day x onward, commitment interest was also due.

That is completely clear to me, but points out that the commitment interest also depends on the costs for the bank itself.

Until now, I also thought that the banks were simply charging a little extra for not drawing down, but perhaps that really isn't true.

How can it be that the commitment interest rate is higher than the agreed nominal interest rate? I mean: Does the bank pay more interest for the provision of money than when it actually disburses the money? And couldn't the bank - like the borrower - simply "draw down everything in advance"? Or are there laws that prohibit this?

Such flexibility just costs.

But that was not the argument from . And honestly, I don't see any increased flexibility there for me as a borrower. I would have more flexibility if I received the money credited to my account and could then directly dispose of it myself. (Yes, I know the bank won't do that, but I still have the impression that this is an outdated practice that should really be cut off as soon as possible.)