Great thanks for all the info!
Funny to see that some lists are so long :-)
I now see that there is not really one dirt tyre that stands out, so in terms of availability that doesn't change much to choose a control tyre. If there was for example one tyre that many big countries used, that could influence our choice.
Some drivers tested a bunch of Jconcepts and proline tyres, and for now the caliber seemed to be the most popular one (wear vs grip etc...)
It will defintaly not be bowtie