Does a true-polymorphed True dragon becoming a Shadow dragon evade ‘dispel’ concerns?

A kobold is True Polymorphed (‘permanently’) into a dragon’s egg (CR 0) and eventually grows up to be an ancient Green dragon. Upon rediscovering / remembering she was a kobold she fears Dispel Magic that would break her Truly Polymorphed form. She seeks to avoid regression to her previous kobold existence.

To secure her draconic shape she abides in the Shadow Realms and gains (True) Shadow dragon form. She now believes, correctly or not, that she safer from various Dispels or Anti-magic zones.

This is, to me (and hopefully my players), a very fun BBEG campaign idea – but there are questions.

Plethora Concerns: – (if possible, i request Stack Exchange answer these generally):

  • Is a True dragon’s egg ‘Challenge Rating 0’ (CR0) – or is this abuse of the True Polymorph spell?

  • Where are these Shadow Realms found (mentioned in the Monster Manual)?

  • Would the dragon be born A Priori with knowledge of her previous kobold life? If so, in a Zone of Truth would she still identify as a [two decade] kobold – or that of a [born & raised / 801+ year old] dragon?

  • Would various TrueSight magics see through her Green dragon form? Would she be a kobold only as long as she was within an Anti-Magic effect or area… and then snap back?

  • if this dragon is dispelled to her former humanoid shape, is she now kobold dust that is more than eight centuries old? If so, this really ups the stake for her interest for that True Shadow dragon change.

  • if she sets some of her flesh aside (such as a finger) whilst in ‘Green’ format (i.e. before attaining shadow format), can she use that flesh for a Clone – thus regain her ‘healthy’ Green-shape dragon body even whilst in this ‘cursed’ Shadow state? If so, what ‘age’ is this new Green body? Is this new Clone now safe from dispel-style magics?

Base / Main Question:

  • Is this Shadow dragon (formerly Green dragon / formerly a kobold) safe from having her form removed by a simple ‘dispel’? Once transformed by this magical darkness, is she effectively a ‘normal’ Shadow dragon forever?

Note that these questions are all True Polymorph related and i hope that this one write-up will suffice. It would help game consistency if this campaign could stay RAW in-game.

If many of these questions are answered directly or indirectly elsewhere, my apologies in advance.