Many of the border transfer stations are inside Poland, Slovakia, Hungary, and Romania, rather than on the Ukraine side. Safe from bombing in theory. I would think it could be a quick build to create unloading loops for unit trains. And loading loops for standard gauge trains with a conveyor in between. Faster than building elevators. Faster than adding a broad gauge rail the many miles to a NATO port. Multiple tracks for each loop so continuous unloading.

Are they building this? Are Ukrainian grain hoppers bottom dump?

There is also a broad gauge line reaching deep into south central Poland. Was for steel but I think underutilized now(pre-war)