..but the 32bit RPi4 driver is v3d, no?
It's about rendering in general, and 2d and 3d.
I cannot say surely about RPi4 (not having one under hands to find out API provided by its VideoCore6 with common V4 driver).
Speaking of RPi3:
Here's what you should get with xorg 3d working using vc4-kms-v3d on an RPi3:
inxi -Ga
API: OpenGL v: 2.1 vendor: broadcom mesa v: 24.1.4 glx-v: 1.4 es-v: 2.0
direct-render: yes renderer: VC4 V3D 2.1 device-ID: 14e4:ffffffff
The same API versions I've seen with v4-fkms-v3d too.
And needless to say about much newer Vulkan and its support by V4.