So the only useful guide I've found is by hackernoon and it is talking about ethereum blockchain explorer setup.
I've been in Bitcoin for several years and now working on my own project. I am looking to develop a blockchain explorer from scratch rather than using existing API (for my personal experience).

What would it really takes in terms of hardware, code requirements and costs?

As far as I understand I first need to setup a Bitcoin node, making sure I have enough storage capacity to handle all historical blocks and transactions (am I right?)
But what am I doing from there? how do I turn it into an database and making my own API?

Does anyone have any guide for it?