Asklemmy

Hard rationing of greenhouse gas emissions

You're more or less describing cap-and-trade, where corporations have a limit of carbon emissions as 'credits' which can be traded on a market. So a company that doesn't produce as much emissions can sell their surplus credits to another company, so the market as a whole doesn't exceed a set amount of CO2 emissions. As it stands, in this or other carbon tax based systems, people pay for emissions in the form of sales tax on CO2 producing products.

wolves

I'd imagine they'd just leave again eventually. If suburbia was an advantageous place for them, they'd already be there.

Nuclear power plants within or adjacent to urban centers, especially in colder climate regions.

Nuclear plants are somewhat geographically restricted to needing to be close to a suitable water source, there's plenty that are next to or inside metropolitan areas. That being said, high voltage transmission means that a plant can still be a few tens of kms outside of a city before transmission losses start to add up. Also, small-scare reactors have been under development for use in remote communities.

Gray water recovery built into homes and municipal water systems.

Any sort of dirty water recovery is more efficient at the municipal scale, and plenty of towns are already doing that.

Urine collection programs for phosphate recovery.

Seems that's not a super easy thing to do (read expensive), but there's research being done... also apparently, a good portion of it in wastewater is from laundry soap... but as in the above, more efficient to just collect all wastewater and process it on a large scale.