Troubles with game optimization for mobile and overall workflow in Unity

Hello everyone, I've been using Unity for several years now, but there have just been a few questions that came to my mind that I can't seem to find any credible answers for online.

The game I am currently working on is a simple endless runner game, with a playerobject which moves either to the left or right by swiping on the screen, and a street, which is made out of short segments, that are stacked behind each other and move below the player, creating an illusion of the player actually moving on the road.

I have always tried keeping my code optimized and simple, as such I for example am now using object pooling instead of instantiation and destruction for the road segments. Since the idea is to have Crossy Road style graphics, I dont need textures and very detailed meshes for the game. Even though the game runs fine on my Laptop, I only achieve about 15 FPS even on modern mobile devices. Looking at the batch amount in the Unity stats I get about 2000, which is apparently too much for mobile devices I have read. However, I cannot remove all of the lighting completely, which drops the batch count to about 1400, and there are barely any gameobjects I can mark as static so that unity can optimize them, because most things are moving and never standing still in the game anyways.

There are many mobile games with great graphics nowadays, so it just cannot be impossible. Therefore I have looked into using other shaders for the materials, but either the built in shaders that unity provides for mobile for some reason need a texture (even though I just need to change the solid color of a specific part of a mesh), and other shaders Ive found online either are not compiling anymore or look really strange ingame.

Furtherthemore, I do not really quite understand the workflow for using models made in Maxon Cinema 4D inside Unity. A friend is responsible for making all the models for the game in Cinema 4D, and he provides them to me in the .dae Collada format, which seemed to be the only format that somewhat worked when imported into Unity. However, upon importing the models, unity messes up all materials on the model, creates new materials in the assets folders, the models pivot point gets all messed up and after some while it just really starts to become a pain to work with models in Unity. Besides that, unity also imports the models submeshes as well, so the model basically ends up with many child objects in the game. This allows us to assign materials to specific parts of the model, however the fact that the model is now composed of many child objects probably makes the game performance suffer alot as well.

I've found the official Unity guides for mobile game optimization to not really go into detail much, and even google searching about the topic of mobile shaders or mobile optimization shows up very little results.

There is no point in continuing the work on the game if the overall structure of the game is unorganized and inefficient. I'd just be happy with having solid colors on the meshes which can also cast and receive hard shadows from the directional light in the scene, just like in may mobile games of this art style. In a professional matter, how would it rather be done: assign the materials for the model in Unity itself or prepare a seperate material file in the modelling program beforehand? My workflow just seems slow overall, and most tutorials don't go onto further detail about this issue.

I know this is alot to ask for, but getting a reference point to start troubleshooting would be a great start for now. Anyways, please excuse me for such a complex and specific question, but I really just ran out of ideas to try. Any help is appreciated!