Update install scripts from main

install.ps1

@@ -98,6 +98,41 @@ function Get-Env {
     $EnvRegisterKey.GetValue($name, $null, $RegistryValueOption)
 }
 
+function Get-TargetTriple() {
+  try {
+    # NOTE: this might return X64 on ARM64 Windows, which is OK since emulation is available.
+    # It works correctly starting in PowerShell Core 7.3 and Windows PowerShell in Win 11 22H2.
+    # Ideally this would just be
+    #   [System.Runtime.InteropServices.RuntimeInformation]::OSArchitecture
+    # but that gets a type from the wrong assembly on Windows PowerShell (i.e. not Core)
+    $a = [System.Reflection.Assembly]::LoadWithPartialName("System.Runtime.InteropServices.RuntimeInformation")
+    $t = $a.GetType("System.Runtime.InteropServices.RuntimeInformation")
+    $p = $t.GetProperty("OSArchitecture")
+    # Possible OSArchitecture Values: https://learn.microsoft.com/dotnet/api/system.runtime.interopservices.architecture
+    # Rust supported platforms: https://doc.rust-lang.org/stable/rustc/platform-support.html
+    switch ($p.GetValue($null).ToString())
+    {
+      "X86" { return "i686-pc-windows-msvc" }
+      "X64" { return "x86_64-pc-windows-msvc" }
+      "Arm" { return "thumbv7a-pc-windows-msvc" }
+      "Arm64" { return "aarch64-pc-windows-msvc" }
+    }
+  } catch {
+    # The above was added in .NET 4.7.1, so Windows PowerShell in versions of Windows
+    # prior to Windows 10 v1709 may not have this API.
+    Write-Verbose "Get-TargetTriple: Exception when trying to determine OS architecture."
+    Write-Verbose $_
+  }
+
+  # This is available in .NET 4.0. We already checked for PS 5, which requires .NET 4.5.
+  Write-Verbose("Get-TargetTriple: falling back to Is64BitOperatingSystem.")
+  if ([System.Environment]::Is64BitOperatingSystem) {
+    return "x86_64-pc-windows-msvc"
+  } else {
+    return "i686-pc-windows-msvc"
+  }
+}
+
 if ($Env:PIXI_VERSION) {
     $PixiVersion = $Env:PIXI_VERSION
 }
@@ -112,10 +147,13 @@ if ($Env:PIXI_NO_PATH_UPDATE) {
 
 # Repository name
 $REPO = 'prefix-dev/pixi'
-$ARCH = 'x86_64'
-$PLATFORM = 'pc-windows-msvc'
+$ARCH = Get-TargetTriple
+
+if (-not @("x86_64-pc-windows-msvc", "aarch64-pc-windows-msvc") -contains $ARCH) {
+    throw "ERROR: could not find binaries for this platform ($ARCH)."
+}
 
-$BINARY = "pixi-$ARCH-$PLATFORM"
+$BINARY = "pixi-$ARCH"
 
 if ($PixiVersion -eq 'latest') {
     $DOWNLOAD_URL = "https://github.com/$REPO/releases/latest/download/$BINARY.zip"