Vegan

Most "egg substitutes" work well for a particular use case of eggs, and not for others. E.g.

• Aquafaba (chick pea water) whips up like egg whites and can be used to make sponge cakes, merengues or similar fluffy sweets.
• Chia or flaxseed/linseed are a good replacement binder for muffins and denser cakes (and good for fibre and protein too).
• Tapioca starch and baking powder can also work to give a bit of leavening for muffins (McKensie vegan baking egg subtitute)
• Ground cashews and/or avocado can be used for some richer desserts like mousses.
• Kala Namak, a dark sulphurous salt which adds the smell and flavour of egg yolk, but doesn't add texture like the above stuff.
• Tumeric is often used to add a bit of yellow colour to make vegan omelettes and scrambles look like eggs.

I haven't seen any subsitutes that are a straight drop in for all purposes of eggs, usually you have to use several depending on the recipe.

There's "just egg", it's pretty close to real scrambled eggs.