This article got me thinking about it: https://www.cbc.ca/news/canada/new-brunswick/radon-testing-libraries-9.6937952

A lot of items could work, but is there something you think we should prioritize first?

I don't think they have measuring devices like that in my library, but sure, that and a geiger counter would be useful. For ecology and saving on the bills, people could make use of energy meter plugs. Or maybe a thermographic camera. Maybe iFixit kits and some tools for people who don't have them at home. And I've seen libraries offer outdoors-games like Kubb and music instruments. I think that's nice, especially for kids and young adults.

Sewing machines
Sewing patterns
Bakeware
Canning kits
Bike Tools
Quilting frames
Hand tools (plumbing, electric, drywall, concrete)

Idk. These are all things that are essential, sometimes. If you don't have a network to borrow from and learn with the library is the best place to start.

I love libraries. Mine just got an embroidery machine and I'm excited to use it for small gifts this Christmas.

I appreciated my university’s media library with video games and consoles. It’s not essential but helps further promote libraries as third spaces

Tool libraries should be more common. From basic renovation tools like saws and hammers, to yardcare tools like mowers and whipper-snippers, to more specialty tools like bike maintenance tools such as torque wrenches with Allen key heads. It's sill to have to own tools that you aren't using almost every week.

We have a pretty decent tool lending library. The people who work there are amazingly helpful, explaining how some things work, or why something else might work better.

My library lends out energy monitors.