Yes there is one equipment slot. The other (unused) slot you can see in the armorer view is going to be for the special weapon in a later version where you'll be able to get one-shot "super weapons" e.g. a wingman, artillery strike, tacnuke, that sort of thing.
Thanks for the feedback, I'm glad you enjoyed it! Good point on the control mapping, I originally built it for PC build so didn't think about shortcut issues at first but now it's on WebGL I definitely need to remap some keys. I expect I'll switch to z, x, c (for: shoot, switch hardpoint, and a new control for using the superweapon).