Soil for potted plants-can I add wood shaving to soil?

Why not.

You can but be sure it is not treated wood.

Also make sure you're. not infusing the soil with bugs of any kind.

I wouldn't do that when there is an inexpensive product made especially to create lighter/aerier soil and I'm referring to "Vermiculite". Walmart sells it and any garden centre should have it as well. I add it to the soil in my pots as it makes the soil less dense so water can reach the roots better and Vermiculite aerates the soil as well.

Recycled plastic soda bottles to make pots lighter

Try using empty pots turned upside down. I put empty plastic pots that come with the plant in mine. They get crushed a little, but my pots are a lot lighter.

Make the pots lighter or the soil mix lighter?