Truly Biodegradable Lagging for Plumbing?

Hello!
I'm hoping this community can help point me to some alternative options for genuinely biodegradable pipe lagging.

We recently moved all our plumbing up into our attic (long story) and now need to lag it. I've been intent from the start on lagging with something biodegradable because mice in the attic will inevitably get at it, and I hate the amount of toxic debris already strewn through the space because of this. I don't want to add more, or to know I'm sending that stuff out into the surrounding nature.

The problem is, when I search for products I find many advertising "100% wool pipe wrap" etc., but it seems these claims are usually misleading. We bought one well known brand (UK) and found the wool is felted against a more polyester-type backing. The company hides this info on a completely unrelated page of their website. Whatever I search, I get noise from all the greenwashing. OR the product is prohibitively expensive.

Can anyone suggest something that's truly a biodegradable product suitable for this purpose? We have limited budget to spend on it, because we'll need to buy it in bulk and/or build it up over time. We also wondered about reusing, e.g., eco wool packaging used for frozen goods, but not sure exactly what's in that, how treated, or how it might react to fire given it's not the intended purpose.

Any advice or suggestions for things we might consider would be much appreciated. - Thank you 🙂

The value of raw wool has plummeted. Twenty years ago in Wales it cost a pound a head to shear, then we'd get a pound per fleece. Now, in Portugal, if you're prepared to take a whole giant builder's bag full, you can pick it up for the cost of going to fetch it. I managed to scrounge a smallish bag off a friend who'd taken too much for an insulation job and made myself a new pillow which I'm enjoying. I bet the situation s similar in Scotland now. Can you find any sheep farmers and ask if they have any bags lurking in a barn?

Thanks so much. I would totally try to do that if it's a viable option. Any idea how home insurers tend to view use of raw materials for these sorts of purposes? I.e. if we were unlucky enough that our house burned down, might the insurers claim it was worsened by use of "off-label" materials because it wasn't a product purchased for the purpose? We all know in a community like this that wool isn't more flammable than the next thing, but I do worry about systemic prejudice against using stuff like that.

As an aside, back when I lived in Wales, not far off 20 years ago, I knew farmers who were burying sheared wool in the ditches cos it cost them to get rid of it otherwise. I used to pick up loads of pretty decent stuff for free to do natural dyeing. So sad.