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 America-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

[ruvr]

Nautilus-Trader can trade german stocks also on german exchanges, if you have a broker account with Interactive Brokers. ISIN identifiers are not relevant, since the stocks can be identified via the general naming scheme of the IB adapter. Just like when you would be trading them in the IB TWS or mobile application.
The decision if and when you want buy or sell is up to you, the developer of a strategy. It has nothing to do with the tool that allows you to do so in an automated manner. You could implement a strategy that respects the ridiculous german tax regulations anytime. Your allegations are pretty negative and are yet another example of deutsche, unangebrachte und anmaßende Überheblichkeit. Please feel free to contribute and provide a solution for the german trading minority if you believe there is demand for it. The problem is the patronizing german government that does not want you to earn money with trading. Not the (unpaid) coders of nautilus-trader. Everyone else in this world is quite happy with what has been accomplished by the nautilus-trader team so far.

[faysou]

"La critique est facile mais l'art est difficile."