You're usually not stuck. There's nothing magical about anyone's nutrients, media or sponges, or seeds. For example, Aerogarden by Miracle-Gro. The sell their own branded nutrient, but you can use any. The needs of the plants don't change with the system. And if you look on Amazon, you'll see many products sold as compatible with Aerogarden And as you learn more, you will better understand how things work and will have even more options. Seeds are seeds. Nothing special there.

Of course, they would like you to buy their kits of seed, grow sponges, and a one-shot nutrient dose. Look a this one:

https://www.amazon.com/Moistenland-Hydroponics-Growing-Germination-Gardening/dp/B07ZCVTTRS/

I don't think it even comes with seeds. I comes with a "starter kit." But note that Amazon suggests buying Aerogarden reseeding kits for it. I think there may have to be a little trimming of the Aerogarden sponges, but the point is they're not different from other similar sponges, and all work. Sponges don't even have to fit the pods perfectly.

Fundamentals: Plants require light, water, nutrient and oxygen. These systems obviously provide light. They do something to aerate the solution or the roots. The details vary, but the roots get the air they need. You provide the water, and you can use any nutrient.

If you depart from using their pricy kit products, you will have questions about using other nutrients, sponges and perhaps choosing plant varieties. That's what this place is here for. If you get stuck for how to use nutrients, just come here and ask.

For perspective, consider one of the most common DIY hydro setups used my many of us. It's a bucket with a hole in the lid to accept a net cup which contains a growing medium that might be based on a sponge, or a peat pellet, or clay pellets, or perlite, etc. We provide air by placing an airstone, aquarium style, in the bucket with an air pump. We use one of any of the standard hydroponic nutrient sets. That's water, nutrient and oxygen. We add an appropriate light for our setup. We can use different nutrient sets. Different growing media. etc. Or we might use a plastic tote instead of a bucket. We're just putting together what you're considering buying for the sake of it being a small package that won't offend on the counter. But we're both doing pretty much the same thing, and able to make choices, because the fundamental operations are alike.