Difficulties with Midgard T860 r18p0 driver on Asus TinkerBoard 2

Platform: Asus TinkerBoard 2S
SoC: Rockchip RK3399
Distro: Debian Bullseye

OS: Linux 5.10.198
Arch: Arm64
GPU: Mali Midgard T-860
Driver: libmali-midgard-t86x-r18p0-wayland-gbm (provided by Rockchip)
Wayland Protocols: 1.20
Weston: 9
WLRoots: 0.11.0
libEGL: 1.3.2
libGLES1: 1.3.2
libGLES2: 1.3.2

Howdy!

I'm working on getting a kiosked browser on the Tinker. Wrestling with the WPE WebKit Cog browser using the DRM platform with the GLES renderer. I can get it to run for a short time but it eventually opens too many file-descriptors to /dev/dri/card0 and crashes. I'm assuming they're not being cleaned up. Are there any known issues related to this with the Mali driver?

I've also tried using the Cog browser with the Wayland backend, but EGL fails to initialize.

EGLDisplay Initialization failed: EGL_NOT_INITIALIZED
Cannot create EGL context: invalid display (last error: EGL_SUCCESS)

Any suggestions on how to fix this or debug it?