Hi there!
I have found a bunch of 8bit royalty free music that the artist doesn't mind being used in erotic games. His name is caled はらゆう.
These themes might be suitable for desert themed levels. You are free to use or not to use these music, its up to the dev's decision.
There are more on his YT channel,
Here's the link and screenshot of permission from Harayuu
https://twitter.com/hara_yuuu/status/1464259241917616133?s=20
In case you don't know how to download music from YouTube,
You may use yt1s.com/en108 to download it. Remember to click away the ads.
Select YouTube to MP3
Insert the youtube link, and then convert it
After that, click "Get link" and then download it
And that's how you download MP3 files from YouTube.
Thank you for reading.