If Pure Land already teaches grace, isn’t the honest conclusion that Buddhism and Christianity are basically the same underneath, so there is nothing to discuss?

The parallel is real and should be honored, but sameness does not follow. Amida is not the Creator, the Pure Land is a stage toward enlightenment rather than communion with God, and the final goal is still the dissolving of the self in nirvana, not resurrection and relationship. What the parallel gives is a starting point of deep agreement, that rescue comes from outside us and is received by trust, from which the differences about who rescues, and into what, can be explored rather than assumed away.