You will likely get more responses to your question if you create a new topic rather than appending it to a five-year-old topic.
As for GRBL, the starting point is the selection of the control board. To me, there seems to be many forks of GRBL, each built around a control board or a class of control boards. Some of these forks seem to be well supported, while others seem almost experimental with limited support. The most mature version (for the MPCNC) is built around the CNC Shield, but with support for only four drivers, you definitely won’t get dual endstop support with this control board.
I did run across this topic some time back where someone implemented a version of GRBL with dual end stops for the Rambo board, but I don’t know how much support there is for that version.