Can this be applied to stock trading in germany?

[Bardo-Konrad]

As german traders know, there is variable fees for each trade and on top there is taxes on every profit.

All backtesting software I tried does not take that into account. In other words, profit from buying and selling has to be enormeous to perform better than buy and hold.

I assume this to be yet another American First software and neglect everyone else(also probably not using isin but only nasdaq symbols).

[faysou]

There is something called fee model in nautilus, you could investigate if it would help you solve what you want to do