Harmony patch to enable developer mode in unity editor requires harmony https://github.com/pardeike/Harmony

PatchDeveloperMode.cs

using System;
using HarmonyLib;
using UnityEditor;
using UnityEngine;
using System.Collections.Generic;
using System.Reflection.Emit;

[HarmonyPatch]
public static class PatchIsSourceBuild
{
    private static IEnumerable<CodeInstruction> ReturnTrueTranspiler(IEnumerable<CodeInstruction> instructions)
    {
        var codes = new List<CodeInstruction>(instructions);
        codes.Clear();
        codes.Add(new CodeInstruction(OpCodes.Ldc_I4_1));
        codes.Add(new CodeInstruction(OpCodes.Ret));

        return codes;
    }

    [HarmonyPatch(typeof(Unsupported), "IsSourceBuild", new Type[] { })]
    public static class IsSourceBuildPatchNoParams
    {
        static IEnumerable<CodeInstruction> Transpiler(IEnumerable<CodeInstruction> instructions)
        {
            return ReturnTrueTranspiler(instructions);
        }
    }
    

    [HarmonyPatch(typeof(Unsupported), "IsSourceBuild", typeof(bool))]
    public static class IsSourceBuildPatchWithBool
    {
        static IEnumerable<CodeInstruction> Transpiler(IEnumerable<CodeInstruction> instructions)
        {
            return ReturnTrueTranspiler(instructions);
        }
    }
    
    [HarmonyPatch(typeof(Unsupported), "IsDeveloperMode")]
    public static class IsDeveloperModePatch
    {
        static IEnumerable<CodeInstruction> Transpiler(IEnumerable<CodeInstruction> instructions)
        {
            return ReturnTrueTranspiler(instructions);
        }
    }
}

[InitializeOnLoad]
public static class PatchDeveloperMode
{
    static PatchDeveloperMode()
    {
        var harmony = new Harmony("com.myrkur.patchDevMode");
        harmony.PatchAll();
        Debug.Log("Harmony patch applied to Unsupported.Developer");

        Debug.Log($"DeveloperMode?: {UnityEditor.Unsupported.IsDeveloperMode()}");
        Debug.Log($"SourceBuild?: {UnityEditor.Unsupported.IsSourceBuild()}");
        Debug.Log($"DeveloperBuild?: {UnityEditor.Unsupported.IsDeveloperBuild()}");
    }
}