That GIF loading code should work on mobiles, I have tested it on my cheap android tablet without problems, soon I will update that topic with full GLB gif loading code (no inline). Still if you trying to load such big gif animation, edit code, there are: gif_max_sprite_width% and ..._heght% change them to higher values, maybe this will help. What error code are you getting from gif loader?
Max texture size may be limited by your hardware, don't know what devices you target but using such big textures isn't best idea, maybe some optimization? Cut only really animated part, or strip one animation in 2 gif-s so they would require much smaller files.
Edit: Furthermore, gif decoding takes some time (it decodes gif, and creates glb sprite that can be used with DRAW_SPRITE/ANIM / Polyvector cmds), so it's best to use it with small files (e.g. like web/ad banners). Best (for such big gif) way would be convert that gif animation on pc to one png/jpg file, load it in GLB and use DRAW_ANIM or custom animation code.