Any ideas for outdoor flooring that can be laid over rocks?

Only solution I can think of is deck tiles

https://www.homedepot.com/b/Lumber-Composites-Decking-Deck-Tiles/N-5yc1vZc224

How big are the rocks? pebbles? large stones, or crushed stone? Large rocks will be a problem with anything you put down.

deck pavers

Are you talking rocks, gravel or pebbles.? Makes a huge difference to what you can do. If it is small gravel you can add 12 " square pavers. They go on sale at Lowe's or Home Depot for about $1 each this time of year.

Deck pavers are meant to sit on top of a deck framework so more difficult to work with as they are heavier.

Maybe a simple deck like this one: https://www.frugalfamilytimes.com/2016/08/how-to-make-hot-tub-deck-for-250-and-2.html?m=1

Pavers are a good choice if you have smaller pebbles that could be pushed around easily. If you have larger rocks, you might have to do something like a pallets, but I'm not sure how steady they'd be if they were on top of the rocks. An outdoor rug might be a possibility also?

Building a small decking over the rocks is the best idea here is some info for you

https://nowrevolutionbook.com/patio-floor-ideas/

What is your goal in covering the rocks? Are you wanting to keep the dirt and weeds down?

Are you wanting to put patio furniture or some other structure such as children's climbing toys outside?

It will be next to impossible to keep an outdoor rug level on rocks. As well, unless you live where it is hot and dry year round, it will develop mildew very quickly due to lack of airflow to keep it dry.

You could use pallets

Maybe use pallets to build a small deck?

We have large square brick blocks as a flooring in the garden.

Rubber mats there like a puzzle they stick together or a outdoor rug

Maybe rubber mats like these: https://amzn.to/35hBIsy

Hope this Helps! Jeremy - https://pahjodesigns.com