Depending on what you're willing to spend Id recommend a water flosser. No plastic pollution, can use tap water as a default or if you're fancy do a mouthwash diluted a bit with water. Insanely efficient, and gives a level of mouth clean I have yet to be able to beat. The first time I used mine I was blown away by how much shit came out of my mouth. Anyway, best of luck!

I'm a gross dude who doesn't take good care of my health. I didn't even really know what flossing was for most of my life. The first time I ever went to a dentist was when a molar crumbled in the middle of a BLT while I was at work during my late twenties. So maybe don't take my dental advice ...

... But I use bamboo floss picks repeatedly so long as they are intact, haven't fallen anywhere contaminated, and have no visible debris on them. Makes me feel a lot less wasteful.

You can get biodegradable bamboo floss; it's what I use. Still single-use, but it's at least not gonna hang around for a thousand years and deteriorate into micro and nano-plastics.

You can get floss holders that will reduce the amount of string you use. They’re not perfect but better than the ‘disposable’ ones.

Well, I am using it multiple times. Similar as work toothbrush.