I have decided to take a second pass at this concept after realizing that perhaps players would appreciate more options for obtaining membrane-bound organelles.
Naturally, as discussed earlier we will need some manner of organelle editor should we choose to allow the player to customize their symbiotes. But what if the organelle editor did not require the prior engulfment of a symbiote? Perhaps it would be preferable for endosymbiosis to be a quick and preferable shortcut to obtaining organelles, that would otherwise require a slow and deliberate process of evolution via the player.
My personal idea is that should the player desire to create a membrane-bound organelle instead of finding one, they must first purchase a basic empty version of it for a price of MP. This would create an organelle consisting of a single hex of cytoplasm that could be further edited using the hypothetical organelle editor, or placed on the cell right away. From there the player could gradually build an organelles overtime instead of the relatively faster act of endosymbiosis.
It would also likely be preferable if this can only be done should the player possess a nucleus. Additionally should we not include an organelle editor, there could be a flat cost to unlock the organelles currently in the game.
Any thoughts?