With regards to vapes, just look on the ground near a sidewalk. I find like 3 or 4 big depleted vapes a day in a US urban area. Closer to 15 or 20 in greater London in the UK.
There are a lot of fun parts inside microwaves (a personal favorite is the high-torque-low-speed-line-voltage motor, which I use to make creepy Halloween decorations) but the caps, transformer, and magnetron are all useful for somewhat... more dangerous... pursuits.
As far as I can tell, this is an urban legend. No consumer microwave oven has ever used beryllium in its magnetron insulators. Military radar ones, yes (and likely where the legend started.) Some specialist test equipment and RF transmitters too, and they all contain prominent warnings of it. Besides its toxicity, it's far more expensive than regular alumina.
Weren't disposable vapes banned in UK in May 2025? Is the problem still that big?