if this can be used to make a type checker for SQL strings like https://github.com/MedFlyt/mfsqlchecker or https://github.com/codemix/ts-sql but for C# I will be stoked!
Although this is nothing to do with string interpolation, the "typed string interpolation" refer to the F# printf format specifiers.
You could also build such tool separately using FSharp.Compiler.Service (possibly using the analyzer infrastructure for ionide: https://github.com/ionide/FSharp.Analyzers.SDK), AFAIU there will be consolidation of this type of tooling relying on FSharp.Compiler.Service in the future to make this integrated to all F# tooling.