I don't think they're actual companies. One of the more recent emails I received contains this bit:

"If you're already employed, I can also support you in taking on additional contract work. I'll guide you through the entire interview process to help you succeed and get hired. In this partnership, your main role would be attending client meetings, while I handle all development and written communication. We would then split the income, with you receiving 40% of the project earnings."

Guy introduced himself as a "senior full-stack developer with over nine years of experience in web, mobile, and iOS development".

Oddly specific number.

Those are known scams. They usually reside in sanctioned countries like North Korea (but I've also gotten a lot of Chinese ones), and they make you bear any legal risk if they try to install backdoors in the client codebase. They also run the same scam with wanting your Upwork or similar credentials.

Ain’t that one of those North Korea “scam” things where they need an intermediary due to sanctions lol I could be very wrong though

I received the exact same email, except they offered me 50% of earnings, so the message sending script probably has some randomization built in. My guess is that their true objective is to get you to install their "interview support app" which is mentioned at the end of the email, I anticipate that it makes your device remotely useful to them, or installs ransomware. But it could be a more involved scam.