[mnau]

This is not a board where you put resistors, capacitors and ICs on a substrate.

These are chip layouts used for fabbing chips. I don't think you will find many open source designs.

EDAs works closely with foundries (TSMC, Samsung, GlobalFoundaries). This is the bleeding edge stuff to get the best performance for NVIdia or AMD or Intel.

As an individual, it's very hard and expensive to fab your chip (though there are companies that pool multiple designs).