So you can have an idea of what the D1 looks like in the Convoy S2+ holster, here are some pics. I happen to have both, but I don’t normally use them in this combination. You can see that it fits and will close, but because of the big head it feels like the velcro wants to separate. The stiff fabric would probably bend more easily over time with use. Perhaps it could work for someone.
Honestly, that doesn’t look any better than the Convoy holster I posted pictures of. The pictures on BG just show a narrow head type of flashlight fitting well into the holster (looks like a S41). Sure the D4 will fit, but I imagine the fat head of the D1 will be bulging out at the top. Pictures of actual use would be helpful.