So, I'm not sure if this applies to other versions of the game yet, as I only have this for PC.

I found out, that the RNG apparently counts from the boot-up of the game, and you can seed it by selecting the difficulty level. Here is the same exact starting puyo, both in Normal and Hard. You can set up an example by spamming the A input to get through the menus as quickly as possible. You should end up with the same colours, if not a recognizable set. It seems to advance this RNG once every half second before you pick a difficulty level (Though, this has not been tested thoroughly, and the internal values not yet checked) The only time it changes the puyo you get seems to be when selectign a difficulty, or advancing to the next stage, meaning you will always get the same series of puyo in the first stage if you apply correct timing.

With this, you can at least learn round one's puyo layouts, and with consistency, maybe even round two and beyond.