The pursuit of a "highly compressed 10MB Ubuntu" is a journey that reveals the incredible flexibility of Linux. You'll likely end up in one of two destinations, depending on your needs.
A 10MB file could barely hold the kernel alone, let alone anything useful. ubuntu highly compressed 10mb
Historically, Ubuntu provided a mini.iso (often around 60-70MB) that allowed a network-based installation. While Canonical has moved away from this method in favor of in the Ubuntu Server ISO, you can still achieve a very minimal installation by choosing minimal options during setup. How to Create a Highly Compressed Linux Image (DIY) The pursuit of a "highly compressed 10MB Ubuntu"
The two primary use-case scenarios can be summarized as follows: let alone anything useful. Historically