I'm looking forward to having the BP8 crew for the upcoming Italian TD line, but someone on the Forums mentioned they were Nation Locked … I confirmed via the description in the game that they are not, but don't want to spend 12k gold to see.
Also the Premium Shop bundle article references the ability to select a nation.
Source: https://www.reddit.com/r/WorldofTanks/comments/v1tliu/battle_pass_8_crew_nation_locked_or_not/