Have you ever looked? They’re extremely common these days
Why no, I decided to reply without even a google.
3u isn't an issue for me personally and I'm not sure if you are being serious or not (if so apologies). But here are some gmk sets with 3u spacebars starting from most recent, a full list would go much further back.
analog dreams r2, lavender, british racing green, haku, dualshot r2, sparta, hazakura, parcel, arch, zooted, metropolis r2, fuji, kouhai, striker r2, dots r2, muted r2