VAR training/match experience for match officials where it's not used domestically perhaps? There's a few refs at the Euro's whose domestic leagues aren't yet blighted ahem don't have VAR so their opportunities for match experience are limited. Saudi Arabia have always been very accommodating in allowing Federations to send people there for VAR experience as are Greece but, as there is this whole global pandemic still sticking around, there have been issues with not being allowed to travel.