AppleScript and JXA scripts to get Now Playing info. Works on macOS 15.4+, including macOS 26 beta 1.

now-playing.js

function run() {
	const MediaRemote = $.NSBundle.bundleWithPath('/System/Library/PrivateFrameworks/MediaRemote.framework/');
	MediaRemote.load
	
	const MRNowPlayingRequest = $.NSClassFromString('MRNowPlayingRequest');
	
	const appName = MRNowPlayingRequest.localNowPlayingPlayerPath.client.displayName;
	const infoDict = MRNowPlayingRequest.localNowPlayingItem.nowPlayingInfo;
	
	const title = infoDict.valueForKey('kMRMediaRemoteNowPlayingInfoTitle');
	const album = infoDict.valueForKey('kMRMediaRemoteNowPlayingInfoAlbum');
	const artist = infoDict.valueForKey('kMRMediaRemoteNowPlayingInfoArtist');
	
	return `${title.js} — ${album.js} — ${artist.js} | ${appName.js}`;
}

now-playing.scpt

use framework "AppKit"

on run
	set MediaRemote to current application's NSBundle's bundleWithPath:"/System/Library/PrivateFrameworks/MediaRemote.framework/"
	MediaRemote's load()
	
	set MRNowPlayingRequest to current application's NSClassFromString("MRNowPlayingRequest")
	
	set appName to MRNowPlayingRequest's localNowPlayingPlayerPath()'s client()'s displayName()
	set infoDict to MRNowPlayingRequest's localNowPlayingItem()'s nowPlayingInfo()
	
	set title to (infoDict's valueForKey:"kMRMediaRemoteNowPlayingInfoTitle") as text
	set album to (infoDict's valueForKey:"kMRMediaRemoteNowPlayingInfoAlbum") as text
	set artist to (infoDict's valueForKey:"kMRMediaRemoteNowPlayingInfoArtist") as text
	
	return title & " - " & album & " - " & artist & " | " & appName
end run

@kreatoo In case it's still relevant: seems MediaRemote can't do it, but MediaPlayer can (but only for Music.app, I think).

use framework "Foundation"
use framework "MediaPlayer"
use scripting additions

-- Get the system-wide music player
set player to current application's MPMusicPlayerController's systemMusicPlayer()

-- Get item for the current track
set nowPlayingItem to player's nowPlayingItem()

if nowPlayingItem is not missing value then
	-- Get artwork as 500x500px PNG image
	set artworkImage to nowPlayingItem's artwork()'s imageWithSize:{500, 500}
	set imageRep to (artworkImage's representations()'s objectAtIndex:0)
	set artworkData to imageRep's representationUsingType:(current application's NSPNGFileType) |properties|:(missing value)
	
	-- Output to downloads directory
	set filePath to POSIX path of (path to downloads folder) & "artwork.png"
	artworkData's writeToFile:filePath atomically:false
else
	return false
end if

JXA equivalent:

(() => {
	ObjC.import('MediaPlayer');
	
	// Get the system-wide music player
	const player = $.MPMusicPlayerController.systemMusicPlayer;
	
	// Get item for the current track
	const currentTrack = player.nowPlayingItem.item;
	
	if (currentTrack) {
		// Get artwork as 500x500px PNG image
		const artworkImage = currentTrack.artwork.imageWithSize((500,500));
		const artworkData = artworkImage.representations.objectAtIndex(0).representationUsingTypeProperties($.NSPNGFileType, $({}));
		
		// Output to downloads directory
		return artworkData.writeToFileAtomically(`${Application('System Events').downloadsFolder.posixPath()}/artwork.png`, false);
	} else {
		return false;
	}
})()