You're in Germany, which means that as a private investor with that low value of investments it's probably not worth going for the 42% taxes that you will have to pay once changing the assets back into currency.

It's much easier to setup a UG ("small" GmbH, aka Unternehmergesellschaft) which owns the shares. A UG has a minimum value of 1EUR, so you can later on even split shares by just letting another shareholder pinch in another EUR. The max value of a UG is GmbH min value - 1 EUR, so it's literally 19.999EUR that can be distributed to shareholders (in their percentage of how much they pinched in). The UG isn't limited in how many external assets it can own, so the legal form is practically made for this kind of investments.

(just a friendly hint)