For DVDs and normal Blu-rays, any drive that can read Blu-rays should work. Only UHD discs need LibreDrive support.
Pioneer drives are considered to have the highest quality, but are hard to get in Germany at the moment. And since they are discontinued they probably never come back.
But there are still some offers in other EU countries if it needs to be a Pioneer. The manufactoring/firmware date shouldn't matter any more, since mike announced that "
all Pioneer drives will be supported as LibreDrive drives in a relatively near future".
External drives:
Just search for blu-ray drive on amazon. They start at around 50 €.
If you want to be future proof look for drives that are mentioned in the
Ultimate UHD drive flashing Guide
The Verbatim 43888 with an LG BU40N (or old models with an Pioneer BDR-UD04) for example:
https://geizhals.de/verbatim-ultra-hd-4 ... 06218.html
There are also 5.25" drive enclosures that allow to use 5.25" drives externally and you will also find them bundled.
Internal drives:
https://geizhals.de/?cat=dvdram&xf=573_ ... roductlist
The cheapest is currently the BH16NS40 for around 70€. Theoretically it should also be flashable to support UHD discs but what I read it depends on the manufacturing date.
For 10€ more you can have the BH16NS55 which is also flashable.