Blazor Server is completely inappropriate for an internet facing site.
The same is not true for Blazor Webassembly, which operates as combination of client and server projects, typically communicating via standard REST calls.
Nope. Being able to write in C# using a vast array of C# libraries in the browser is orders of magnitude better than writing in JS or even TS. C# is enormously superior to JS and superior to TS.
If you care more about development experience than users, that's fine, but in the case of SPA, JS frameworks will be faster and lighter.
For me the problem with TypeScript is not the language, JS/TS are fine for me, the problem is the entire toolchain - NodeJS, all the node_modules, configuration files, the need to compile.
Maybe Svelte, where they got rid of TypeScript and the types are now in JSDoc, could be a compromise.