I suggest not trying to do this.
You can certainly make most of .NET8 work with a pure OSS toolchain, but your overall development experience is going to be destitute compared to that of the official tool chain. To be clear - I think paid alternatives, such as Rider are fantastic too, but even so I've had some trouble at the edges with paid 3rd party (Blazor apps, UWP, etc).
At the end of the day, you have to ask yourself about what your hourly rate is. If you are going to spend a 20 hour premium per week bandaging up a "free" .NET toolchain, whereas the official, $100/m stack costs you 1-2 hours, which one actually costs you more? What are your principles worth in terms of your free time?