This is what I put under my black huckleberries.

https://www.finegardening.com/plant/creeping-raspberry-rubus-pentalobus

I think the ajuga will be fine. I find it no more difficult to control than any other groundcover and a lot more behaved than many. And a lot more tolerant of foot traffic than liriope would be.

The rubus is probably my favorite groundcover but very iffy below a zone 7. @kitasei2, aren't you located upper New York? I doubt the rubus would be suitable in that location.

Im in the Hudson River Valley which is just north of New York City. Rubus would be zone pushing but if you tell me it has edible raspberries I’ll try it! We have lots of wild raspberries if that means anything. Gallica, I have liriope that is spreading like molasses even though i divide it spring and fall. Too shady maybe. Gal, do you think i need to worry about ajuga stealing water and nutrients from blueberries?

Ajuga is certainly worth a try. It will have to be weeded or mowed high if that is acceptable. Have a look at Mazus reptans.

Mazus reptans - Plant Finder (missouribotanicalgarden.org)

There are two types of liriope. One spreads, the other doesn't. They seem to be very confused. I got mine from one of the Cary Arboretum plant sales, if you knew/remember them. So I knew it was the spreading kind because that's how they got it.

"There are two types of liriope. One spreads, the other doesn't. They seem to be very confused."

Not confused at all :-) Liriope spicata is an aggressive spreader - Liriope muscari is a clumper.

kitasei2, the rubus does produce a gold to orange edible berry. But very infrequently and it is only mildly tasty.

I would attempt to keep a plant-free zone around the base of the blueberries, the same as one would do with mulch. This allows watering and fertilizing as needed to happen without conflict. And I would do that with any groundcover used.

I've heard enough stories from people who bought what was labelled L. spicata, that didn't spread for years, and people who bought what was labelled L. muscari that took over their bed that I think it is safe to say they are confused.

If you have a way of reliably telling the two apart in a nursery container, it would be useful information to have.

Both species will spread but rhizomatous spicata will spread more rapidly and aggressively than fibrous rooted muscari ever will. As to the differences, muscari has wider and longer/taller leaves than spicata and taller flower stalks that produce dense clusters of violet blue flowers that resemble grape hyacinths in bloom (hence the species name).

Part of the confusion may be that those who are not familiar with the plants and their difference will interpret any kind of spreading as "taking over their garden". Many folks tend to exaggerate the issues they have with spreading plants :-) And all non-woody plants have a tendency to spread outwardly given time and good growing conditions.