For programmers, it's a mixed bag. There are positions where a PhD is strongly favored or required, but for far more positions, a PhD is often viewed as a negative because of fear that they will be too blue-sky and abstract to do down-to-earth work.
There are positions (FAANG companies are infamous for this) that strongly prefer or outright require at least a degree, often in a subject viewed as relevant (nominally C.S. but math and physics are often considered to be potentially viable alternate areas). But other companies care far more about work experience, and may give little weight to presence or lack of a degree.
Similar comments apply to which university it was: some companies and some parts of the world are highly biased towards prestige universities, other companies and other parts of the world less so.
And then there are the certificates you mentioned. In my experience, those are considered to have some value compared to no degree plus no job experience, but otherwise not very useful at all -- and sometimes there's prejudice against certificates (where it's considered better to not have certification regardless of other factors).
So there's no absolute rule. But degrees from good schools usually help.
Canada has a strict requirement for engineers (electrical, civil, etc) to pass a qualification test of some sort, and I was told (by ex-pat Canadians) that it's not legal to do engineering work without that. Plus they get a special ring to wear to show their status (not kidding, I've seen them).
Scuba: I have "Rescue Diver" certification (search, rescue, first aid, etc), which would be required for certain diving-related jobs, and the next higher level of certification carries legal obligations -- e.g. it's illegal to panic and run away (swim away) from divers in distress if one has the Master Diver cert.
Short of that, I have met divers who don't like to dive with people who do not have at least the Rescue Diver cert (because "everyone in the party should be capable of expertly helping everyone else").
That's a pretty open-ended question. There so many areas of potential expertise in today's complex world.
Hmm, I just remembered a guy who collected certifications in, he said, all fields, not related to his profession. He had dozens, including things like HVAC repair. Unusual hobby.