[OkayPhysicist]

There really isn't hours worth of material to put together a browser extension. You can read all the relevant docs in tops an hour, but you can follow the MDN tutorial on it to get the "inject some Javascript into pages with a url matching this pattern" level in less than 10 minutes.

[KurSix]

Yeah, logging "Hello World" from a content script takes 10 minutes. But then you run into Manifest V3 service worker lifecycles, bypassing CSP on the host page, and syncing state across tabs, and suddenly your "quick one-hour project" turns into a completely burned weekend

[skydhash]

Also most extensions are open sources. You can hack something from just glancing at the code of some samples.