I can manage and manipulate my entities just fine with custom classes, the only current problem is rendering them. I have multiple large entities made of tiles which can rotate independently of each other, and the tiles need to change constantly. How can I render these sprites? Unity can barely handle 10k sprites, I need 100k minimum.
Depends on what you actually use those for.
If it’s interactible tiles, with colliders or some other CPU heavy components, you can’t in a normal way. Unity forces the scene manipulation to be mono threaded, which severly limits the possibiilities.
You can try looking at Unity ECS which helps manipulation of thousands of objects. But it is in beta stage and not fully ready for production.
If you simply need to display them, as suggested by Stratosome, use particles.
What are you trying to draw that requires 100,000 sprites?
Drawing a single mesh with 100,000 faces is definitely possible. However, drawing 100,000 meshes with one face each is not. (This is how sprites are rendered) This is not an issue with Unity, this is how graphics cards are designed.
Depending on how many unique textures you need, you can store them all in a texture-atlas or texture-array, and then use a special shader to render a single mesh with 100,000 quads or more.