I bought one of these "silicone sounds" a few years ago and absolutely love it.

https://www.mr-s-leather.com/silicone-sound-4-sizes

Technique and safety wise it is much more forgiving than a catheter or metal sound. There is very little chance of scratching/damage. While it does not have the "Holy f*ck! There is a rod sticking out of my dick!" factor, I have a lot of positive feed back on the sensation and when removing it, it stretches and looks even longer--so you have that image.

I sanitise it with pretty harsh hospital chemicals and then lightly boiling water to remove said chemicals. I thought it would fall apart after a few uses, but is still going.