I've certainly seen sliding doors on a track where the tracks are side-by-side. The doors slide in the tracks, so where they meet when both closed, one is offset from the other. I've seen this for closets, so where the doors meet isn't a big deal. In a bathroom, if they don't meet perfectly and close without a crack, you're going to have a problem. I'd consider just having a narrower door.

You might look at tambor doors. Most are made for cabinets or pantries or to go up and down, but you might be able to DIY a suitable solution.

Sigrid's idea of cutting down a regular sized door to the size you need would be the best option and the least amount of configuring two doors.

Looks like they are called telescopic pocket doors.

https://www.eclisse.us/en-us/products/collection/classic-collection/telescopic-single/

Hardware:

https://www.slidup.com/us/product-category/telescopic-door-hardware/?srsltid=AfmBOorzY29Owg5-Hg9ylD40yCFWf3-TrRQkiL2KENu8gkLuUeW8ZM6C

One more:

https://www.richelieu.com/us/en/category/sliding-system-solutions/sliding-solutions-for-architectural-applications/hawa-telescopic-systems-80-2-80-3-40-4/1061888/sku-WEBKIT1220412

This might be an obvious question, but have you thought of having a door that opens into the hallway instead of into the bathroom? We switched the door swing on our small bathroom door.

We installed very heavy custom made and high quality pocket doors for our kitchen. They keep in sound and orders, which is what you want in a bathroom door too. However, the act of closing a pocket door is not one that is friendly to rushing to the bathroom. Who uses this bathroom, how often? I would not want pocket doors on a bathroom.