N64 had a 4KB texture cache while the Ps1 had a 2KB cache. But the N64's mip-mapping requirement meant that it essentially had 2KB + lower resolution maps.

The streaming helped it a lot but I think the cost of larger carts was a big drag on what developers could do. It is one thing to stream textures but if you cannot afford the cart size in the first place it becomes merely academic.

I don’t think storage space was an issue for graphics in particular. Remember the base system had 4MB memory and 320x240 resolution

The real problem was different. The PS1 cache was a real cache, managed transparently by the hardware. Textures could take the full 1 MB of VRAM (minus the framebuffer, of course).

In contrast, the N64 had a 4 kB texture RAM. That's it, all your textures for the current mesh had to fit in just 4 kB. If you wanted bigger textures, you had to come up with all sort of programming tricks.