Script that re-entitles the macOS Valheim app to be moddable with runtime code-injection wrappers like BepInEx. For arm64, you'd probably need to still run the app with an x86_64 emulator like Apple Rosetta 2. You may need to run with sudo to re-sign the App Store version in /Applications.

make_mac_valheim_moddable.sh

#!/usr/bin/env sh
set -e

VALHEIM_APP_PATH=${1:-"${HOME}/Library/Application Support/Steam/SteamApps/common/Valheim/valheim.app"}
BEPINEX_FRIENDLY_ENTITLEMENTS='<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "https://www.apple.com/DTDs/PropertyList-1.0.dtd"><plist version="1.0"><dict><key>com.apple.security.cs.allow-jit</key><true/><key>com.apple.security.cs.disable-library-validation</key><true/><key>com.apple.security.device.bluetooth</key><true/><key>com.apple.security.device.usb</key><true/><key>com.apple.security.network.client</key><true/><key>com.apple.security.network.server</key><true/><key>com.apple.security.cs.allow-dyld-environment-variables</key><true/></dict></plist>'
ENTITLEMENTS_PATH='/tmp/revised_valheim_entitlements.plist'

main() {
	read -p "
Re-signing and re-entitling Valheim at
$VALHEIM_APP_PATH

This will remove any Iron Gate or Coffee Stain signatures and replace them with adhoc signatures
that no longer identify the developer or publisher. It does this while entitling the app to have
runtime code injected for the sake of modding. The changes will be overwritten when you upgrade
or reinstall the app. This will likely be fixed in the official version soon anyway and you should
probably just wait.

Do you want to continue anyway (y/n)?
" choice
	case "$choice" in
		  y|Y|[yY]es ) re_sign_bins_with_dyld_hacks;;
		  n|N ) exit 0;;
		  * ) echo "didn't understand, exiting" && exit;;
	esac
}

re_sign_bins_with_dyld_hacks() {
	echo $BEPINEX_FRIENDLY_ENTITLEMENTS > "${ENTITLEMENTS_PATH}"
	contents_path="${VALHEIM_APP_PATH}/Contents"

	for f in "${contents_path}/Frameworks"/*.dylib "${contents_path}/Plugins"/*.dylib "${contents_path}/Plugins"/*.bundle
		do re_sign_bin "${f}"
	done
	re_sign_bin "${contents_path}/MacOS/Valheim"
	re_sign_bin "${VALHEIM_APP_PATH}"
}

re_sign_bin() {
	echo "Re-signing $1"
	codesign --sign - -vvvv --force --options runtime --entitlements "${ENTITLEMENTS_PATH}" "$1"
}

main