I don't see AfD supporting debt brake reform, because they present themselves as fiscal hawks (and I reckon AfD wants CDU to fail so they can pick up voters from them).
But the Greens and whoever else should definitely negotiate with CDU for spending on vital infrastructure like electrical grid, rail, energy storage, etc. German economy is wrecked right now due to lack of demand, and Germany has excess industrial capacity to build out these physical investments that will pay off in the future.
Also sadly for Germany, if CDU fails, next election you might be looking at AfD led government like what happened in Netherlands.
Feasible, yes. Practical, hard to say. Good idea, yes.
RISC-V is open-source architecture based in Switzerland (although it started in University of California).
One thing going for it is China is spending billions a year towards RISC-V adoption so they do not get sanctioned by the US. You need money and engineers working on it towards these type of open source to compete with existing players.