Maybe 7Zip extraction? I haven't tested it.

SrcMod/Shell/GlobalUsings.cs

@@ -1,4 +1,6 @@
 global using Nerd_STF.Mathematics;
+global using SharpCompress.Archives.SevenZip;
+global using SharpCompress.Readers;
 global using SrcMod.Shell;
 global using SrcMod.Shell.Modules.ObjectModels;
 global using System;

SrcMod/Shell/Modules/CompressionModule.cs

@@ -1,8 +1,9 @@
-using System.Reflection.Emit;
+namespace SrcMod.Shell.Modules;
-using System.Xml.Linq;
-
-namespace SrcMod.Shell.Modules;
 
+// Some things that can be extracted can't be compressed by SharpCompress.
+// In the future I might replace it with my own, but that'll take a *really*
+// long time and I'm already planning to do that for the valve compression formats,
+// so I'll seethe for now.
 [Module("compress")]
 public static class CompressionModule
 {
@@ -228,4 +229,6 @@ public static class CompressionModule
             name = $"Compressed a file or folder into a zip archive located at \"{destination}\""
         });
     }
+
+    // 7z can't be compressed.
 }

SrcMod/Shell/Modules/ExtractionModule.cs

@@ -114,4 +114,32 @@ public static class ExtractionModule
         zip.Dispose();
         reader.Dispose();
     }
+
+    [Command("7z")]
+    [Command("7zip")]
+    [Command("sevenzip")]
+    public static void Extract7Zip(string source, string? destination = null)
+    {
+        if (!File.Exists(source)) throw new($"No file exists at \"{source}\".");
+
+        if (destination is null)
+        {
+            string full = Path.GetFullPath(source);
+            string folder = Program.Shell!.WorkingDirectory;
+            string name = Path.GetFileNameWithoutExtension(full);
+
+            destination = $"{folder}\\{name}";
+        }
+
+        if (!Directory.Exists(destination)) Directory.CreateDirectory(destination);
+
+        FileStream reader = new(source, FileMode.Open);
+        SevenZipArchive zip = SevenZipArchive.Open(source);
+
+        IReader data = zip.ExtractAllEntries();
+        data.WriteAllToDirectory(destination);
+
+        zip.Dispose();
+        reader.Dispose();
+    }
 }

SrcMod/Shell/Shell.cs

@@ -4,7 +4,7 @@ public class Shell
 {
     public const string Author = "That_One_Nerd";
     public const string Name = "SrcMod";
-    public const string Version = "Alpha 0.3";
+    public const string Version = "Alpha 0.3.0";
 
     public readonly string? ShellDirectory;
 

SrcMod/Shell/Shell.csproj

@@ -31,6 +31,7 @@
 
   <ItemGroup>
     <PackageReference Include="Nerd_STF" Version="2.3.2" />
+    <PackageReference Include="SharpCompress" Version="0.33.0" />
   </ItemGroup>
 
 </Project>