L2 has been around for a while. In terms of open source protocols you've got LN, so that's the main one that provides instant super cheap payments. And then there are various other networks / sidechains and whatnot already existing or being developed by companies that can do a variety of things.

L2 just isn't used much yet because it isn't needed. Payments are barely needed because there is barely any merchant adoption. It will take time for the relevant use cases to actually start being in demand to cause a need to L2 usage to actually grow. But L2 is definitely here and been here for a while.