Mine are teenagers (14 and 17), and I've never heard of colostrum harvesting! It seems like an utter load of faff for absolutely nothing, for the average woman.
I did have tummy time recommended to me to strengthen their necks, and saw no reason not to put them on a blanket on the floor for a few minutes a day - and they do have lovely round heads, haha.
What I did at the time, which wasn't recommended even then, (although the nurse actually tucked them in with me at night in the hospital!) was co-sleeping. Without a pillow and with one blanket, both my kids survived co-sleeping well and by 6 months had practically learnt to breastfeed themselves without waking me up 😂
The thing I don't get is the baby sleeping bags, which were gaining in popularity when mine were born. But when napping during the day or evening in their cot, my kids had the same blankets my mother used with me as a baby. In winter, it was: viella nightie, knitted woollen vest and booties, swaddled in a cloth nappy, and then tucked in well under a sheet and several wool blankets. Sometimes with a knitted woollen hat if the house was cold.
These days, it seems like all babies are in cotton/polyester, and have nothing but a sleeping bag.