I had this done a few years ago [0] and the article is pretty much spot-on. Especially about the process - the audiologist will insert a tiny cotton ball allll the way down in your ear, then squirt the polymer in (which is creepy feeling). You wait for it to cure, and they pull it out & trim any excess.

Note that you can now get custom sleeves which slip over commercial earbuds like the Apple AirPods, so you can get a perfect fit and they're less likely to fall out. You get to choose your color. I went with different colors for the right & left ears, to make telling them apart easier.

They are noise isolating, so you will have to pay attention to your surroundings (traffic, people approaching you from behind, a coworker trying to get your attention). But they don't block enough sound to make them effective at loud concerts or at a shooting range. Wear proper hearing protection for those events.

Speaking of which - watch your volume levels. It's super easy to play them too loud and damage your hearing. Take breaks every 30-40 minutes.

[0] Many thanks to RK Audiology in Austin. https://rkaudiology.com/custom-fit/