Leaving Germany, bringing ETF with me?

Hi people,

I am living in Germany and about to start to invest in an accumulating ETF, like the FTSE All-World A2PKXG. I intend to do so for the long term (20, 30 years).

I have not chosen a broker yet, but I would probably go for a German one as they automatically deal with the taxes.

What would I do if I leave Germany in the future? Most likely it would be to another EU country.

Is there a German broker which allows to transfer my ETF to a broker in the new country? A small fee is acceptable.

Will I have to pay Germany a ~25% tax on my unrealized profit for moving my ETF abroad, even if I have not sold it?