Respectfully, but your talking points are very common and very wrong.
> Adopt modular nuclear reactors, and produce hundreds/thousands of them yearly.
Nuclear reactors need fossile fuels to work (in the supply chain): To sustain nuclear you need to have a thriving militaro-industrial complex, which in all sorts of manner requires vast ressources which you must somehow buy (or steal depending or your political views) from global south countries.
The problem here is very simply framed: we've thrived on tons of cheap energy and now this source is tarishing. It's pretty clear there is no miracle alternative: nothing around us is going to have the same combination of cheapness, massive volume, energy density and ease of use (neither nuclear nor renewable). We can improve some alternative stuff but there's really nothing on the same level. That is a fact. Now if you're running short on something, you spare it. And in fact it's pretty practical. One should be blind not to see how a small part of the world is hilariously over-consuming (energy, raw material, food, investment). Knowledge has exploded and it's now easier than ever to build things that last. That are passive in energy during use, that are cheap to produce in terms of energy input and non-renewable material contained. This will of course be at expense of economic growth since it will drive consumption down. But that is actually what we need. Of course it needs cultural changes, but like seriously, who is satisfied with the current doxa? Trust in institutions in dominant countries is at record low, there is gonna be a (obviously more or less gradual) reboot, with changes in lifestyle and social order. So we better choose it instead of having it imposed.
> Figure out how to get to a global population of 4 billion: ie massive family planning drive in Africa/West Asia encouraging 1/0 children. (Keep in mind this is just the population level from 1974).
Ugggh. You and me are the problem, not some poor smuck in Nigeria or Bengladesh, who's energy consumption in a year is probably comparable to ours in a month. We're the one that are making them badly extract their ressources, who are paying for them to work, to whom they ship broken things, who are doing tourism in their countries. Think about it for one moment and then please stop using this colonialist talk point which is fallatious ("poor people reproduce uncontrollably"). There are numerous reasons for that to happen and our domination on them (past and present) is a big one.
Precision: of course we have to "help them" up their materialistic well being, and that encompasses having better healthcare support for women, contraception etc. But it's improductive and actually violent and authoritarian for us to do it directly and without giving away power, money and knowledge. And perhaps we could start by not hindering them to do so, like EU countries are currently doing with Covid vaccines (i'm saying Covid but this is routine mafia racket work which is pervasive in all industrial domains).
edit: i even forgot to answer to one of your points:
> Electrify transport.
This is a moonshot. For one, autonomous transport needs high density energy storage and has locality between source and use. Too bad electricity is like impossible to store directly and has as main benefit to be transportable quite easily over long distances. Our vehicules are designed for fuel, they just cannot be reused as is with such a different energy source. The one way electricity is useful for transport is if you manage to profit from its benefits: trolleybus and rail. Again if you go back enough in your assumptions and think about the real problem there's one solution which is always overlooked: scale it down and do less transportation ffs. Globalization has enabled some radically new stuff which need planetary scale to actually be possible. But these things are a minority: it's high-tech stuff. Let's just make every local group of countries produce it's own simple things locally again (as in: what is needed to have 80% of our lifestandard) and we'll cut global transport by X%. Stop designing cities like everyone has their personal car. Stop depleting countrysides from local services (yes, it's local human-labour intensive to maintain).
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All the things i presented are actual solutions which would need some thinking to go through and lots of reorganizing, but crucially they aren't depending on some magical technology popping up. We know they can work. The real question is now: do we want to keep the worlds power structure and thus depend on a moonshot to make things work or do we accept to stop doing what has been central to maintain the domination of global north on global south and just do the easy obvious thing? It fine to defend the second choice, but you gotta know what your defending.