> For example my employer doesn’t provide a work Github account… but while I have the option to use my personal one, I can also sign up for a separate one.
Apologizing for being the Well Actually Guy, but GitHub's terms of service include the line "One person or legal entity may maintain no more than one free Account". If your employer doesn't provide a work account for you or use Enterprise GitHub, then technically you can only have both a personal and a work account if one of them is paid. My suspicion is that GitHub doesn't go out of their way to enforce this, but it's there.
As far as Apple IDs go, there's absolutely nothing that prevents you from having multiple ones, though, no. I think I've had work Apple IDs in the past. You can also have separate Apple Store accounts and Apple ID accounts (which I do, although that's something of an accident of history in my case). While I've logged into my Apple Store account on a company-owned device so I could use some of my personal applications (ones that would be appropriate for work, for the record), I would absolutely not want to log into my personal Apple ID -- the one that accesses my personal mail, calendar, iCloud Drive, etc. -- on a company-owned device.
The problem with that is when you sign a work contract with your employer, there's typically a clause there that also says something along the lines of, "whatever uses you may have of company resources becomes the property of the company".
So clearly, there can be a delineation of personal vs. corporate entities there if I don't elect, for example, to use my personal Github account versus my work Github accout, which I signed up for using my company email address. If under that scenario, the company cannot claim ownership over my personal email account, then clearly my person is not the same legal entity as my employer and I can keep both free accounts without violating Github's T&C, isn't that correct?
IANAL and all the requisite disclaimers, but GitHub explicitly recommends that you use one free account for both personal and work stuff, and there's fairly granular organization-level access controls built into the platform to keep those things separate. If I have a personal GitHub account and FooBarCo adds me to one of their GitHub organizations, that does not magically make any repos I have access to that are not part of their GitHub organization the legal property of FooBarCo.
Apologizing for being the Well Actually Guy, but GitHub's terms of service include the line "One person or legal entity may maintain no more than one free Account". If your employer doesn't provide a work account for you or use Enterprise GitHub, then technically you can only have both a personal and a work account if one of them is paid. My suspicion is that GitHub doesn't go out of their way to enforce this, but it's there.
As far as Apple IDs go, there's absolutely nothing that prevents you from having multiple ones, though, no. I think I've had work Apple IDs in the past. You can also have separate Apple Store accounts and Apple ID accounts (which I do, although that's something of an accident of history in my case). While I've logged into my Apple Store account on a company-owned device so I could use some of my personal applications (ones that would be appropriate for work, for the record), I would absolutely not want to log into my personal Apple ID -- the one that accesses my personal mail, calendar, iCloud Drive, etc. -- on a company-owned device.