Hi,
I know you are "over there" and this place is "over here", but sometimes you just need parts wherever you can find them. I'm going to stick with "legacy" Gasgas and have found, what I think, is the best source yet for parts.
Enduropuro in Italy:
https://www.enduropuro.it/shop/en/
The trick is that they have the Rieju bikes and parts, and since Rieju took over all tooling and inventory for the legacy bikes, they have or can get any part, if at all possible. For example, do you want a VForce 4 complete reed cage for GG 200/250/300 2005-2019 and Rieju 2020-present? (It's the same part according to parts lists). No problem, in stock and at a good price.
They have parts lists/fiche for all bikes, all years, so you can do your research. They also have aftermarket parts.
I don't work there and have no connection to them, Im just going to keep my Gassers alive for a long time, since they are perfect for my application and I can always find lightly used cheap gassers locally.