Open Book Chess Variant Feature

Hello chess folks, I have an idea I wanted to share and I was curious of how open people would be about such a variant.

The variant is rather simple. It's still standard chess, but both players have access and can decide together how far and in which direction to play book theory. The goal would be to speed up the chess opening and quickly get into a middle game at which point the help would stop and the game would continue just like any normal chess game. It would be a way to bypass the opening formalities and possibly practice more specific lines.

It would make sense if it had a separate rating from normal chess and possibly establish limitations on how the book theory helps.

The advantage of this would be to expose players to what a good theorical opening looks like. Just being aware of these openings lines a little more in depth would give many players the chance to understand what a position demands and why certain moves are considered best. I think this would be really beneficial for players in general because it could help them get on the right footing, but also learn new openings more quickly if they're already strong players trying to expand their repertoire. 

I guess I didn't consider what happens if both players doesn't want to play the same theory. Maybe players would take turns to decide theory ? Anyway, there's still a few things worth thinking about design wise, but it felt like an interesting idea for this point in time with the pandemic and AlphaZero making an appearance. Some sort of semi assisted chess that helps players build the right habits and get past the opening phase on an equal footing without being worried about these pesky mates in 4.

I guess it's just because I've been dreaming of having a chess sandbox where I can practice rare lines like a Panteldakis Countergambit without being worried about my opponent not playing into it. Who knows, maybe this already exists and I just missed the boat. If that's the case, sorry, I didn't realize.