not sure, it's been a while since I had to figure all that out ๐ค I'd imagine you can put in a budget, generate a QR code via desktop and pay it with your phone for now.
Oh, you could go with some super easy like cake wallet..use spark. Or Rizful.com you can make a custodial lightning wallet with nwc so you can set up a sub.
i think you go to https://theforest.nostr1.com/ , log in to your npub then there should be an option to pay the subscription via lightning if I recall.