I'm pleased to find I can simply change the .mp4 extender to .gif
on the Output File specification in Mplay: File->Export->ffmpeg mp4...
to Save an Animated .gif image file that displays reasonably well in Chrome & Edge browsers!

But I'm hoping for a way to apply suitable ffmpeg settings
to achieve less-dithered/less-quantized-color results
for better looking display in Other apps' colorspaces (like 'Slack' chat for ex.)

I've noticed indications online that Roman Kikhtenko ONCE had an 'ffmpeg gif...' mplay Export option in 2017 :
CGTIPS 02 — EXPORT GIF FROM HOUDINI MPLAY #cgtips #houdini #python


? Q : Would anyone share with me a way I might Add an 'ffmpeg gif...' mplay Export option, please ?

-mike lafave

I got this answer from support:

"The mplay movie encoders are registered in $HFS/houdini/MVexport. You can register your own encoder either directly in that file, or, as I'd recommend instead, in a similar file elsewhere in your houdini path. If you use the same label, you can hide the original encoder. The default ffmpeg encoder script is found in $HFS/houdini/scripts/mvexport/ffmpeg.py if you want to start from that."

Thank you, Matt, for this prompt reply!

I definitely think of You as the expert on Houdini .gif things
and I'm aiming to apply your ffmpeg paletteuse advice
to get .gif image files that will look better
than the dithered ones do when they get scaled down.

Thanks again!
-mike