If you already suggested this engine to be included in the meta info, the actual Itch staff that deals with these things did not approve. Like they also did not for the hundreds of other tools that are not available in the meta-info.
Maybe Itch will overhaul and exapand the meta section someday. I specifically do not like that there is a Unity tag and a Unity meta-info and that those lists are not the same. Stuff like that might be solved with aliases.
In the meantime, if you want to have the engine you used listed on your game's info box, use a regular tag. https://itch.io/games/tag-pocket-platformer and can also credit it in your game's description.