I mean, it's not a stretch to see how you can use native pattern matching with ErrorOr result types.

    #!/usr/local/share/dotnet/dotnet run
    #:package ErrorOr@2.0.1
    using ErrorOr;

    var computeRiskFactor = ErrorOr<decimal> ()
        => 0.5m; // Just an example

    var applyAdjustments = ErrorOr<decimal> (decimal baseRiskFactor)
        => baseRiskFactor + 0.1m; // Just an example

    var approvalDecision = computeRiskFactor()
        .Then(applyAdjustments)
        .Match(
            riskFactor => riskFactor switch {
                < 0.5m => "Approved",
                < 0.75m and >= 0.5m => "Approved with Conditions",
                >= 0.75m and < 0.9m => "Manual Review",
                _ => "Declined"
            },
            errors => "Error computing risk factor"
        );

    Console.WriteLine($"Loan application: {approvalDecision}");

(Fully contained program, BTW)

Here's the OCaml version:

    let compute_risk_factor () = 0.5

    let apply_adjustments base_risk_factor = base_risk_factor +. 0.1

    let approval_decision =
      let risk_factor = compute_risk_factor () |> apply_adjustments in
      match risk_factor with
      | r when r < 0.5 -> "Approved"
      | r when r < 0.75 -> "Approved with Conditions"
      | r when r < 0.9 -> "Manual Review"
      | _ -> "Declined"

    let () =
      print_endline approval_decision

Still not functional enough?...Or you just don't like C#? No point moving goal posts.