OK I'm bored and thought I would join in the pointless navel gazing ...

A "theory of everything" with respect to the physical universe is entirely feasible. Its not necessary or indeed especially useful for such a theory to have to encompass abstractions such as ideas or theories themselves. Ideas are abstract emergent properties of physical matter that is organised in a certain way (i.e. our neurons) and those organisational pattern are not uniquely dependent on exact physical properties of the individual particles that form the informational patterns.

Nor do I see any compelling reason as to why such a theory needs to be infinitely complex. Anyway please desist with this infinity shit - it will drive you mad, as it has done some famous mathematicians.

WRT relativity vs quantum mechanics, clearly there is some unifying framework that connects them since for example we cannot use quantum effects to breach relativity at the macro level e.g. using them to transfer information faster than light. Its just that we cannot for whatever reason perceive it, most likely because our sensory apparatus (both natural and constructed) only exists in some subset of the dimensions that make up the complete system.