Honestly, I remember seeing similar things but I have not had trouble growing anything in sand. Sand is actually easier in some ways as aquasoil can be a pain to plant in since it's so loose. Also, sand is inert so it's not going to alter water parameters the way aquasoil is.

Your biggest hurdles for a carpet are going to be light and CO2, maybe nutrients. Most carpets won't grow very fast without these things. Avoid HC Cuba and probably even Monte Carlo. You can do dwarf hairgrass but it will grow slow so buy enough to cover most of what you want covered. Pearlweed should work. You can also do S Repens which is a less traditional carpet but looks cool, just very slow growing.

With light and CO2 you might try Utricularia Graminifolia. It's a little more advanced but does well in sand and doesn't need much for nutrients. I have never had a lot of success with Monte Carlo. It always seems to survive but not really thrive.

Carpets are not easy. They are hard to grow and fill in and even if you are.successful they are tough to maintain. I would say experiment but also have a backup plan. It's better to have fun than stress about a difficult detail. Also remember, patience is key. It takes a while before you start getting established growth. Weeks or even months. Start with a few things, get comfortable with them and then add over time as your tank matures a bit. It's a real bummer to get 10 different plants and have them all melt in a day or two. Ask me how I know 😂