The Fianchetto Variation has the following moves: 1. e4 c5 2. d4 cxd4 3. c3 dxc3 4. Nxc3 Nc6 5. Nf3 g6 6. Bc4
Black has the intention to develop his pieces without making structural concessions in the center with the moves d6 or e6. This line has drawbacks in the weakness of the f7 square and it can be difficult to develop his KN, but it has been tried.
1.e4 c5 2.d4 cxd4 3.c3 g6 4.cxd4 d5 5.exd5 transposes to the Panov Attack
If you get a playable middle game any opening is OK. If you like this opening, then there’s nothing wrong with playing it. However, moves like a3, which have nothing to do with development or pressure on the center (two elementary opening principles), cannot be theoretically “good.” This would appear to be born out in database statistics. If you want to know what constitutes a "good variation", see what the Grandmasters play. If you don't see top-flight players employing a system, it PROBABLY has little value. That said, most of us won't be playing any GM's, so we have a wider choice of openings. If you like this system, then by all means, play it.