This is the last update we had from Openreach reagrding the last G.INP test, in August 2020:
"Unfortunately the larger loads towards the end of the trial have highlighted some unforeseeable issues whereby CPE [VDSL broadband routers etc.] would fail to sync, despite the GEA Service Test usually showing the circuit as testing ok. Our early root-cause analysis has indicated that this is related to an issue in the DSLAM."
But unfortunately, nothing since then. I wonder if they will just give up on rolling it out now, after several unsuccessful tests and the COVID-19 pandemic dragging on.