Hello everyone:)
I own some BTC that are stored ATM in an exchange (yes, i know it is bad....).
I would like to store them offline for the very very long term. My aim would be to
create a brand new wallet, with for instance Electrum, and move the funds
into it.
That seems very ambitious. We can revisit your idea some other time but this might not be as easily done as you might think so it is really better if you move your bitcoin some place else for now as you try and navigate through the things you need to do in order to make the said wallet.
All the technicalities, complexities and then the actual application might take too long that you might not be able to address what you wanted to in the first place.