I've been thinking about this a little lately.
The aquarium hobby has it made with regard to the variety of sterile, tissue-cultured plants. The only trouble seems to be that the companies offering these things can't seem to keep up with demand, and I get the impression that becoming a dealer of certain brands is prohibitively difficult. I've been trying to find sterile, tissue cultured Phyllanthus fluitans for ages, and while Tropica offers this, I cannot find it for sale ANYWHERE. There are only 17 Tropica dealers in the US, according to their website. Two local businesses were carrying their line around the same time a couple years ago, and then the stuff just disappeared. What gives? Criminy.
This may be slightly off topic, but it seems relevant. While I'm on the subject of tissue cultured plants- I'm a little reluctant to tell, lest it make these plants even harder to come by- these things are excellent in frog tanks. A lot of plants used in the aquascaping hobby are plants that tend to live along the margins of bodies of water. The more CO2 they require, the better they seem to do out of the water, I've noticed. The reason they require supplemental CO2 when fully submersed is probably a consequence of the fact that they live in very wet conditions, but many tend to prefer to grow above the water line. Riccia, Micranthemum, Alternanthera, Anubias, Bucephelandra, and Eleocharis are some I like.
The mosses offered this way are a little easier to find, but they still take a while to get established. I've been thinking about buying a few tissue cultures and growing them out across a bed of either ABG, sphagnum (I know, moss on moss sounds ridiculous, but it can work), aquarium foam, tree fern panel, or a layer of perlite, vermiculite, or similar in a Sterilite tub to form a carpet that I can tear into mats and place as needed.
I have the end of a bag of NEHerp that I plan to experiment with in this way. The NEHerp mix is primarily sphagnum moss and what looks a lot like pearl moss, and a smattering of random ferns and things I haven't identified yet. It takes forever to get started sometimes. Once established, mosses seem fairly tolerant of drying out, but when getting them going, nothing short of being soaked all the time seems to work. Java moss and pearl moss have done very well for me. I haven't tried others in a tank yet. I've got Christmas moss going on a kokedama, but I had to keep that thing in saran wrap for three-ish weeks before the moss really got going. Now, it can get crispy between waterings without missing a beat. If I hadn't wrapped it, I doubt it would have taken.
I wonder if saran-wrapping moss in a tank while it's establishing might help. That sounds like another little project I might undertake.
By the way, I've always thought the yogurt thing was disgusting. Agar seems like a better choice, but it can also mold. Springtails love it, though!