How will the leveling experience in Shadowlands affect Hunter pet taming in different "expansions?"

Hi there. I am a relatively new player. I haven’t leveled very high yet and I started playing during BfA.

Regarding Shadowlands and choosing an expansion to level through (because I am not at max level yet): will selecting BfA allow me access to other regions of the map as well to tame pets (I play a hunter)? For example, I really like the Panthara you can tame in the Broken Isles during the Legion expansion. If I want to tame a panthara, or a wolfhawk, should i choose to level through the Legion expansion or BfA, because it seems every subsequent expansion includes the regions of the previous ones? For example: purchasing the BfA complete edition gave me access to all other expansion zones, or so I thought.

Perhaps nothing has been said about how this will work in Shadowlands yet. If anyone has any information, though, I’d really appreciate it!