Hippo setup is a possible choice here, but you may want to consider 4...e6 then ...Nd7, before ...b6, ...Bb7. Refer below link for some examples of master level games, scroll to bottom.
https://www.chess.com/clubs/forum/view/whites-favorite-plans-vs-hippo
Can you explain why you would play 4. e6...Nd7 before b6. Is it to stop white from playing moves like e5 or d5?
IMO, playing ...b6 at this juncture gives away your opening plan. Surely a Hippo or a double fianchetto is the plan and a longer wait to push back on the center. If you are a strong Hippo player, you may try to goad White to play another common pawn move, f4. This four pawn attack is menacing but for the Hippo player, a fun challenge since a Hippomite can find good strategies to punish this advanced pawn group.
Otherwise, a double fianchetto is somewhat weak after an ...e6 and ...d6 idea because White will have time to defend the fourth rank while black will become cramped. Therefore, in large parts, common (as in the Hippo) is ...a7 and h7... interjected to defend the often exploited g5 and b5 squares. Following the ...b6 with Bb7 is obvious, but a mute development in the eye of the "Tiger" as a "nowhere to go" scenario. Much more must be done to really activate this Bishop.
Finally, ...b6 is really nothing more than a common transposition and is playable. IMO it shows your hand too soon. IMO, lacing this particular opening with ...d6, ...a6 threatening ...b5, Nbd7 threatening ...c5, ...e6, Nge7 gets to a Hippo but keeps White on there toes the whole time. Are they going to play ...c5? What about ...e5 and an Averbakh type structure? Sometimes, depending on White's aggression, Nh6 threatens ...f5!
This kind of leads to some of my personal concerns that the Hippo is one of the HARDER openings to learn. Why HARDER? The newly minted Hippo player may like the idea of being able to player 6, 7, or 8 moves automatically but, without learning when and where to "strike", may end up playing to passively and drowning. White has so many options to strike at a Hippo while typically having more tempo to work with that Black must study and know the game AFTER the 10th move!
- Two cents
The Averbakh System has always been alarming to me because I never liked the main lines. Here is the Averbakh System if you don't know what I'm talking about:
My question is simply, can I play b6 here? My thoughts are to create a structure similar to the hippo and attack whites massive center like you would in the hippo. Can I play b6 and how would I go about doing that?