Is there anywhere else that’s switched to proportional representation, run-off voting, or similar from FPTP?

https://www.fairvote.ca/how-democracies-adopted-proportional-representation/

How does it affect things like regional representation

https://www.fairvote.ca/localrepresentation/

For example, if we go with MMP, https://www.fairvote.ca/mixed-member-proportional/

If you prefer a video format, https://youtu.be/D3guVBhKmDc

Seems like it creates instances where the candidate from some ridings gets a seat with fewer votes than the other candidate.

Not too sure what you mean by this, but maybe MMP would give you an idea as to what would happen, and whether the scenario you’re thinking of would actually be possible? Lemme know.

I think the urban/rural divide is only going to get worse as technology leads to more migration to urban areas even though it’s the rural population that’s taking care of the fundamentals in our economy.

I don’t really believe that technology is the leading factor to the migration, but economic factors are. This isn’t to say that our farms aren’t profitable (I believe they are and should be), but there simply are more options of work in urban areas. Given that farms take up a lot of space, population ends up being sparse, and so do economic opportunities. It doesn’t have to stay that way of course, perhaps we could rethink how rural life works, e.g. rural Japan, but that’s not only a change in culture but likely also a multi-year work, so I digress.

PR isn’t one electoral system but more so a principle that some systems follow. So it makes more sense to talk about the different systems that implement PR, and see how they can work for us, or if we can give it a bit of a twist so that it can work for us.

Fairvote has another proposed system that aims at the rural/urban divide: https://www.fairvote.ca/rural-urban-proportional/

Is there anywhere else that’s switched to proportional representation, run-off voting, or similar from FPTP?

New Zealand, Australia.

How does it affect things like regional representation.

Regional representation is mostly the same. Even in the current situation, we can have parachute candidates: candidates that don't come from the region are allowed to put up their name for consideration and be elected. So we don't really have good regional representation to begin with. And if that's the case, regional representation isn't as relevant as people might perceive it to be (that's not to say it isn't important!).

even though it’s the rural population that’s taking care of the fundamentals in our economy.

The economy is far too complex to capture in this statement alone.

...and as everyone knows the value of a human (and therefor the influence they should have over society) is measured in how many dollars they contribute to the economy. that's why our current system of government is so just!