Depends on where you live and how much legislative hassle you want to deal with.
Pretty much everywhere any UAV over 250g now requires BS licences and registration.
If you want to avoid that there’s thankfully been loads of growth in sub 250g quads. I have no idea what the all up weight of a Gremlin is but the current hot ticket for urban and hassle free sport flying is the “Toothpick” class. These use high power 1103-1104 size brushless motors and F4 micro boards with 2 or 3s mini lipo. Ready made the Happymodel Sailfly is great value and will work off 2-400 mah stick packs like a Whoop or 2s lipo packs.
To make a toothpick Kabab FPV’s original Toothpick frame, a micro all in one board and some motors/props plus a camera and VTX is all you need. Search Toothpick class drone on Google and check out Kebab FPV, Drone Mesh and Albert Kim. Tomoquads make some awesome lightweight frames as well.
If you want a 5” then there’s lots of options and builds out there, look for one you understand and stay away from any F3/Naze32/CCD32 trash bundle deals on EBay.