How to create sidebar from “scratch”?

Technically “off topic” here as your actual question is open-ended and there is lots of room for opinion. https://wordpress.stackexchange.com/help/dont-ask

Sidebars and widgets are a perfect way to organize these elements. Keep in mind these are simply tools to organize blocks for repeated use in various locations.

So, officially, my answers to your two questions are:

Yes. No.

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