Created a gauge swatch:

Cast-on 30 sts
Knit 4 rows garter
Knit 28 rows in this manner:
Odd: Knit whole row
Even: Knit 4 sts, Purl 22 sts, Knit 4 sts
Knit 4 more rows garter
Cast-off

Pre-wash, measures:
6.25” wide
4.25” tall

Post-wash, measures:
5.25-5.75” wide
3.75” tall

So, lost roughly 1/2 inch around. I did not block.

Wash on cold/cold, regular wash, with a bunch of towels, in a net bag. Let it go through full cycle. Put it in dryer for a good 2 hours along with other rough materials. It barely felted in the slightest! Not sure how others have done it, but confirmed what I’ve read that not-fully-wool-yarn won’t felt properly.