Any opinions on whether Alex Falkenham's "BLTR" tattoo removal cream could work on other pigment?

BLTR is many years away from FDA approval. Its efficacy on *any* color ink is unknown.
While the proposed mechanism of BLTR sounds tantalizing, there are many important questions to be answered by pre-clinical and clinical study. For example, when a macrophage "commits cell suicide" and releases its pigment contents, what then? Will the pigment crystals move? Are they even small enough to move? Will another macrophage come along and re-engulf them, putting us back at square one? Will the cytolytic action stay local, or will it affect distant macrophages off busy doing other jobs? (Gosh, I hope not!) These particular immune cells have their own very interesting ways of communicating with each other chemically, so you want to tinker carefully. This is the value of methodical drug testing, to find these things out.
I have my fingers crossed that there will be a new player in tattoo removal, but it's going to be a long wait.

They don't work. Don't waste your time or money on these. At best they do nothing and at worst, they will scar you. Tattoos are extremely difficult to remove and OTC medications will not work.