If you don’t want to use a real luffa made from the luffa gourd, you can use a simple cotton washcloth to scrub. They can last for decades, wash in the laundry with your towels, and biodegrade/compost after a long and useful life.

My partner knit (or crotcheted maybe) a mitten out of hemp. It’s held up now for several years and works great.

I was thinking the same thing recently. I purchased a silicone body scrubber. So far it works fine. It doesn’t lather as much as a luffa but it works for my needs. I think the people talking about luffas aren’t looking at the transportation costs and manufacturing costs. Even if the luffa is eco friendly, it isn’t eco friendly to get it delivered a couple times a year. The first R is reduce.

Avilana® Silicone Body Scrubber with Advanced Hygiene Technology, Gentle Exfoliating Body Scrubber That’s Easy to Clean, Lathers Well, Longer Lasting, The Ultimate Loofah Replacement (S1, DARK GRAY) https://a.co/d/02cDt3p

You could try an actual luffa, which is from a squash-like plant.

luffas are a type of cucumber, it’s their fibers that form the bathroom sponge – luffas are the original, the “unrecycled plastics” are the alternative

EDIT: as for the buy-it-for-life aspect, they’ll break down over time, but they are compostable and you can just grow new replacements

I use a soap bag. Place a bar of soap in the bag. Soap lathers well through the loose weave. Sisal or cotton fibers exfoliate your skin as you scrub. Then hang it by the drawstring to dry after each use.

I have been using mine for several years. I do not know the brand, but these look similar: soap saver bag from Golden Forrest and sisal soap bag from Olivaris Organics.