Ground-up or Top-down

When building Linux Distributions, you will be faced with two approaches - ground-up and top-down

Each has its own advantages and use cases depending on the goals and constraints of the project

Ground-up is mimimal by default, you have hight control, every component can be fine-tuned for optimizing function of your distribution. Installs what you need means it is lightweight and has lower surface area for security cover. It requires high level of expertise, understanding dependencies, compiling techniques, configuring systems, handling incompatibilities. Yocto project, buildroot, linux-from-scratch are some well-known opensource projects to use for this approach.

Top-down approach starts with fully-featured Linux distribution and then removes or customizes components to meet specific needs. It's quicker to implement but might have more overhead due to pre-installed components. Derivative distributions e.g. debian-based or fedara-based for particular usecase comes under top-down approach.

There is a new approach to assembling distributions which has declarative configuration, reproducibility, atomic upgrades, and isolation as core principles which are highly desired devops and clound environments or other Infrastructure as Code environments. NixOS is one such distribution, complemented with a prebuilt Nix store and powerful package manager Nix, makes it a compelling choice. But it does have a steep learning curve.

Use a ground-up approach when control, performance, and a minimal system are priorities, especially in constrained environments. Use a top-down approach when time-to-deployment and ease of use are key, especially in general-purpose or large-scale deployments where a base system can be stripped or expanded.