Both the SPD and Greens are against all of these ideas as far as I can remember at the moment, so there's hardly a realistic chance for any of these ideas to get pushed through by a very small coalition partner like the Left would be.
Nah not really. On a federal level that might be true but some of that is already happening (or at least being considered) on federal state level, so it's not too outlandish to think that this could happen on federal level.
"(323) Existenzsichernde Sozialleistungen sollen Schritt für Schritt zusammengeführt und
Btw. those were just a few examples that I could think of. I didn't check the election manifesto for any of these parties to search for stuff I don't like.
Nuclear power getting phased out is very much a consequence of the accident in Tschernobyl about ten years earlier, similar to how the black-yellow coalition accelerated the outphasing of nuclear power in response to the public reaction to the accident in Fukushima. But it's clear that the CDU likes the narrative of the Greens being to blame for the lack of energy resources when none of this would be a problem if the most recent black-red governments hadn't slowed down the expansion of renewable energy in the last several years.
Any sources for that or at least the reason how the government slowed down the expansion? The problems are found elsewhere.
On federal state level: Long administrative approval processes (several years), wind turbine distance rules and whether power lines should be over- or underground...
lawsuits filed by environmental organizations (how ironic) and last but not least residents who don't want them in their area for whatever reason.
Also, what I forgot to address yesterday is your statement that conservative votes account for roughly 50% in Germany. You only get to this figure by including votes for the AfD, but there's a difference between being conservative and being a nutjob. Furthermore, that a coalition without the CDU is possible now is owed to the CDU losing their votes from four years ago to left-leaning parties, not the FDP or AfD on the right side of the political spectrum because those two parties combined are almost exactly at the same value as four years ago. That strongly suggests that many of the people in the center see a need for change, because the SPD and CDU aren't far apart on the political spectrum; I would categorize their overall policies as center-left and center-right, respectively.
Well that's just guesswork at the moment. Here's the graphic from 2017 which clearly shows that AfD and FDP benefitted the most. Yeah it could be a little different this time around but you also fail to acknowledge that more CDU voters die from old age compared to other parties. So they're more likely to lose voters naturally because the demographic is slowly changing. The smaller parties have almost doubled with Free Voters being the strongest currently. Lastly, voter turnout can be an explanation as well.
And lastly, Germany is infamous for its boneheaded federalism, so red-green-red in the government wouldn't have that much of an impact on the individual parts of Germany who do as they see fit anyway. Nobody is getting ignored when the CDU doesn't lead the country as a whole. Well, nobody of the reasonable people I should say; AfD followers are a different breed who have conspiracy theories and warped perceptions of pretty much everything, so life is tough for them as long as the AfD doesn't reach its Endsieg.
I think you underestimate the legislative power of the Bundestag. I recommend reading articles 70-74 of the Basic Law.