People seem to be overestimating bounties a lot. Unless Oda stops giving a shit, there's no way for Zoro and Sanji to get over 1b.
Like, look at what Luffy had to do:
>Created a plot to kill BM, destroyed one of her islands, escaped with one poneglyph, defeated 2 YC.
Now look at what Sanji and Zoro did:
Zoro: tried to block the attack of the 2 yonko and failed, having to be rescued by Law. Tried to do a kamikaze attack on kaido and did some light wounds that did not affect his combat abilities in a significant way. Wasted a couple of hours/minutes incapacited and them managed to defeat a YC after a gruesome battle, being out of commission for the rest of the raid.
Sanji: defeated by one of the tobiroppo had to be rescued by another SH. After that fought 2 YC alongside Marco. Finally defeated a YC. Was incapacitated for a time and ended up helping prostitutes during the end part of the raid.
Even looking in the best way possible is not enough for a billion.