Interceptors こんなのなら割と実用的かなぁ

Gen.cs

namespace ConsoleApp1
{
    using System.Runtime.CompilerServices;

    file class Gen
    {
        [InterceptsLocation(@"F:\src\ConsoleApp1\ConsoleApp1\Program.cs", 1, 16)]
        public static ReadOnlySpan<byte> M1(string _) => [1, 2, 3, 10, 11, 12, 100, 200, 255];
        [InterceptsLocation(@"F:\src\ConsoleApp1\ConsoleApp1\Program.cs", 2, 16)]
        public static ReadOnlySpan<byte> M2(string _) => [0x83, 0x01, 0x01, 0x02, 0xC3, 0x61, 0x62, 0x63, 0x03, 0xA2, 0xFF, 0x00];
    }
}

namespace System.Runtime.CompilerServices
{
    [Diagnostics.Conditional("CompileTimeOnly")]
    [AttributeUsage(AttributeTargets.Method, AllowMultiple = true)]
    file sealed class InterceptsLocationAttribute : Attribute
    {
        public InterceptsLocationAttribute(string path, int lineNumber, int columnNumber)
        {
            _ = path;
            _ = lineNumber;
            _ = columnNumber;
        }
    }
}

Lib.cs

using System.Diagnostics.CodeAnalysis;
using System.Globalization;

internal class Binary
{
    public static ReadOnlySpan<byte> Dec([ConstantExpected] string value) => Parse(value, NumberStyles.Integer);

    public static ReadOnlySpan<byte> Hex([ConstantExpected] string value) => Parse(value, NumberStyles.HexNumber);

    private static ReadOnlySpan<byte> Parse(string value, NumberStyles style)
    {
        var s = value.AsSpan();
        var list = new List<byte>();
        foreach (var range in s.Split(' '))
        {
            var span = s[range];
            if (span.IsEmpty) continue;
            list.Add(byte.Parse(span, style, CultureInfo.InvariantCulture));
        }
        return list.ToArray();
    }
}

Program.cs

var d = Binary.Dec("1 2 3 10 11 12 100 200 255");
var h = Binary.Hex("83 01 01 02 C3 61 62 63 03 A2 FF 00");

foreach (var i in d) Console.WriteLine(i);
foreach (var i in h) Console.WriteLine(i);