At Aldi, I snagged a couple of these in 2.75" pots for $2/each. NOID on anything they had. In trying to find out what they are, my Google Pixel app says, Selenicereus anthonyanus but in diving a little deeper and checking messages here, I notice there might be another. Is it possible to ID without it being in flower?

I've never grown them. I've read they can be in a richer, more moist mix than a tropical succulent/cactus mix. Any thoughts?

I think S.Anthonianus has slightly more pointed leaves and yours could be E.Anguliger.
The former has pointed purple and white medium blooms and is notoriously hard to get it to flower, the latter has small fragrant white / yellow blooms and flowers easily. Both bloom in summer.
Re: potting medium. As with all epiphyllums a free draining mix is essential. Cactus/succulent mix would be best.
Good luck.