That literally depends on whether Bitcoin will win. Ecash is best on Bitcoin but in the end it's just an accounting method for already existing assets. Ecash should also exist for fiat but fiat is full of gatekeepers.

Is there any way to use the 55-bit ordinal space alongside the lightning network to lock specific onchain sats inside an ecash token?

Like a "fractional" uxto that is enforced by the lightning network?