So this is what I did:
Got two (identical) shrimp from a local pet store that had good yelp reviews. However, their water quality was kind of bad: Ammonia 0.25, Nitrite 0, nitrate 30+! pH 8, GH 14, KH 8, TDS 410. Despite this, the shrimp were actively eating at the time I put them in my drip container. I added some Prime.
Separate the two shrimp into tubs floating in my main tank. One gets the super slow drip acclimation, the other one somewhat faster.
Did a 1 day drip acclimation to my own water which is: temp 74F pH 6.5-6.8, GH 6 KH 0-1, TDS 150 Ammonia / nitrite /nitrate = 0. (This is intended to be a caridina tank with buffered substrate, but I know that neos can do ok in these conditions too) I use RO water + salty shrimp mineralizer.
When I first put the shrimp in, and the first 30 hours or so, the shrimp was acting very normal and shrimp-like, e.g. walking around and grazing, eating and pooping a lot. But from the second day onwards, it just tends to stand around stationary in one spot not moving. Sometimes (rarely) it will graze a little bit, but most of the time it is frozen. The other shrimp is in the super-slow acclimation bin (TDS is 220 by now) seems to be slowly eating.
The reason for the super-slow acclimation is that I read this article:
https://www.advancedplantedtank.com/transferring-livestock.html
Where the guy claims that for KH differences greater than 3 you should transition them over a week or more.