"Fill pot with 2" of soil then place one uncracked raw egg in the pot. As it decomposes, it will serve as a natural fertilizer."
This is a pin that made me do a double take. You see, eggshells are honestly a great compost addition so it's easy to think maybe by tossing in the whole egg, it can work just as well. However, there's a handful of problems that can come up when you just toss a whole egg into compost, let alone in a pot you're planting in.
Not only do whole eggs attract pests like raccoons, mice, rats and skunks, inviting them to dig up whatever you planted in order to get to the egg, but the egg will go bad before it starts to decompose. Quite a few people have mentioned how when they tossed a whole, uncracked eggs into their compost a few of them over time basically exploded. And that is one smell I wouldn't wish on anyone. Thoughts are mixed on if you should even add whole eggs to your compost pile; those who do it recommend either cracking and stirring it into the compost pile or burying it very deeply so pests can't get to it. That's not an easy solution however when we're talking about pots.
All in all I'd say this is a bad idea. It's best just to stick with compost or if you feel the need to add eggs, use the shells only to be on the safe side.