Ask HN: How should I go about having multiple employers?

Become a contractor/consultant. Specific steps depend on your exact location, permanent residence and citizenship. Generally speaking, make a self-employment license or a corporation, advertise yourself just like if you'd be looking for a job, say that you work on a B2B contract, do the job, send invoices, profit.

Depends on how you're representing yourself to your "customer".

BTW - you're not expecting your "customer" to provide you with health insurance, a pension, paid time off, or any other benefits that only go to real employees, are you?

If you want to work for multiple customers, become a freelancer where you decide your own hours and ensure that there is no conflict of interest. Otherwise you are doing a disservice to your actual employer who expects your attention for the hours you are hired for, provides benefits like Health Insurance and everything else, trusts you that you will be there when they need you and in good faith expect you to not work for someone else at the same time.

Suddenly with remote work, this question has been coming up a lot and boggles my mind. How can someone do this in good faith ? ANother reason why fully remote work will be very tough for all employers.

Check out the OverEmployed subreddit: https://old.reddit.com/r/overemployed/ I am not advocating this, but you have guys on there with 2 or 3 jobs.

Read developer hegemony and start a software consulting company.