Alright science enjoyers, I have collected some data for us
Ordered the yarn on Sunday, still feeling absolutely terrible.
Package arrived Tuesday around noon, later that day I managed to record a short video for Ko-fi members, and by that night OH was saying "you sound a lot less cough-ey".
Next few days, made sure to pet the yarn and look at the yarn and take photos of the yarn. A lingering cough remains, and my voice took a while to come back but otherwise the recovery seems complete.
Things definitely took a turn for the better on Tuesday, that's all I'm saying.