the point behind this opening is to either grab d5 or prevent the opponent from gaining a tempo on the d4 knight.

does it work?

3...Bb5+ helps him develop. Nc3 is better!!

Interesting idea, I guess. After the natural continuation 9...a6 10.Bxf6 gxf6 11.Nd4 Rg8, it looks pretty unclear. If 12.Kf2 or O-O, 12...Qb6 could be trouble for white. Maybe just 12.Qe2 followed by O-O-O and white is good.

3.Bb5+ (russian variation) is perfectly sound. Countless GM games have been played in this line, it has a slightly drawish reputation which is probably not entirely deserved. recapturing with 4...Qxd7! is considered more precise by some authors, since black usually wants that knight on c6, but  Nxd7 is also perfectly playable. A recent high-level game in this line is Carlsen-Nepomniatchy (draw).

Your idea is to delay this bishop move a little, and for sure it must be playable. However what does white gain from interpolating 3.d4 cxd4 4.Nxd4 Nf6? in my view nothing, since black can't prevent him from playing d4 after 3.Bb5+ and the bishop exchange. He loses quite a bit in flexibility instead, since after 3.Bb5+ he can still choose different plans: he can play d4 more or less trasposing to your line, but he can also play for a marozky bind as carlsen did in that game, or choose a more restrained approach depending  on black response. Instead in your line he is already committed to an early d4 with Nc3.

Therefore i would say that 5.Bb5+ is very playable but not entirely logical, and that you should rather go for 3.Bb5+ if you like this sort of line, since it leaves your option more open and is therefore harder to face for black.