I found that I not alone with the GPD Pocket battery issue. It is
recommended to contact GPD directly a request a new one.
So I did. And they promptly answered that they cannot send the battery
to the Czech Republic.
OK. I find a dealer in Spain which has these batteries available
(others in Europe don't have them).. And they told me the same: they
cannot ship batteries to the Czech Republic.
Oops.
I only hope that the Pocket 2 (which I already have) has a bit better
battery.