Magic Trashman has written a tutorial on how to padhack a Neo Geo Mini controller to DB15 (arcade/Neo Geo direct connection) and add a clicky microswitch d-pad to it. It's a relatively complex mod involving custom 3D prints, but MT has been offering pre-modified controllers for sale through Twitter.
Controllers for Neo Geo CD for sale
Impressive analog stick with all dimensions positioning that provides super accuracy Start and Select function buttons A, B, C, D buttons with classic
NEOGEO mini PAD(Black)
The Good D-Pad - insert credit
New controllers with good D-Pads
Neo Geo Controller Pad AES MVS & CD 15-pin with custom clicky thumbstick Modified By NK mini-PAD Arcade Game Acessory - AliExpress
8BitDo NeoGeo Wireless Controller
8BitDo NEOGEO Wireless Controller (2.4GHz)
Neo Geo CD Controller conversion
Do USB-C Adapters work with Game Controllers? NeoGeo Mini Pad Tested! [Review]
Neo Geo Pocket – History & Games
SmokeMonster on X: The @MagicTrashman clicky Neo Geo Mini controller is DB15 modded too, for arcade & Neo Geo MVS/AES/CD. / X
Testing the NeoGeo Pad 2 on PS3 via Brook Adapter