If I recall correctly the image loaded, then the animation happened and was smooth, but it didn't animate the instant it loaded. Is that what you are asking?
Yes it looks like the browser start loading the gif file and display the first frame then wait for the missing data. That's good.
You can use wifi on the Tesla to bridge onto another cell network through a mobile device running as a hotspot. I think local IP addresses are firewalled out for security reasons so you might need to remap a non-local address to local.
I prefer to work locally for 2 reasons :
-mirroring will work even if you loose the LTE network
-it will be a lot faster and smoother
All we need is a smart way to push the local URL to the browser. Can be a simple bookmark for testing.
We can easily verify if the browser can connect a local web server running on the hotspot:
-Install this app
https://play.google.com/store/apps/details?id=net.mj.android.httpd in you phone
-Start the WIFI hotspot first and then the http server
-connect Tesla to hotspot
-try to open the server URL from Tesla browser (be careful it's using the 8080 port by default) Mine is
http://192.168.43.1:8080 but address can be different on your device. The URL is displayed in the Android httpd app.
I'm pretty sure this will work but it's safer to check before coding .