If your game is 32kb or less, go on Catskull Electronics' 32kb cart and select Custom ROM. It's really cheap and works effectively.
It's 64kb. I couldn't keep it to 32kb because background animations and the song put it over.
Look around a bit, there are a few with more storage somewhere on the internet. I'd love to see it on a real gameboy!
it will fit on one of the Chinese bootleg carts from aliexpress that’s what I used to create a short run of my game
Maybe down the road it would be cool to make some carts. I'm still waiting on my GB flashcart I ordered months ago lol. Also thanks again for your tutorials. They helped a lot with this game!
GBDK has some improved compression support in the most recent release. If you wanted to revisit this it might be easier to do now. Happy to answer questions as well.
Also, here's how I compress and decompressed the music in Petris (which took some work to keep under 32k).