"If a company wants to hire me, I expect them to spend hours going through my site and assess my previous open source work, and how and why I might be fit for them, etc. "

I hate to say it, but ... it's unlikely to happen. The problem for you is that for most companies, there are plenty of leads in the sea.

For everyone like you, there are 100 who aren't. The likelihood you are objectively a better candidate than all those folks is ... low

Until that changes, your request pretty much won't happen.

(As for spamming, the author says it was 5 years ago, "My first thought was "what took them so long?" - it has been five years since my last contact with a Google recruiter."

I don't think i would qualify reaching out every 5 years as spamming)