Why haven't companies taken this approach? There's powder and transdermal but I see no pill. Or is there a pill product I haven't heard about? Pill is the most convenient IMO..

T-up and TST Powercell
First, because it is a one-dose per day product.
Second, the powder is pleasant-tasting and can be mixed and downed in 15 seconds
third, tableting is an expensive process that should be saved for products that need to be dosed multiple times per day or are impossible to swallow as a powder, either due to taste or something else (like Berberine).
Evolutionary Muse - Inspire to Evolve
BPS - Where Body meets Performance
Flawless Skin Couture - We give you the tools to make you Flawless
There are plenty of pill versions. The companies here have the best price and you know it works for people here. Support the board!
Who has transdermal?
Exactly, the Hard FX PowerPack will give you more then a full dose of D-Aspartic Acid in pill form, i personally like taking it in pill form as its much easier then trying to drink it. You also get a lot of supporting ingredients that potentiate the effects of DAA, for example Forslean will act through similar pathway increase effectivness of DAA as well it also contains 7-MF which is a natural AI creating a positive feedback loop resulting in more test production.
Although your getting full dose of DAA you can see its much more then just a DAA product.