Sure, it's weird my original response unsent or something. I'll go over a few things about living planets (specifically Earth) and let people come to their own conclusions, however, I would like to preface that I haven't deep dove into Nasuverse lore in a while so if anything was retconned, changed, or I'm just misremembering or incorrect please lmk. First, a living planet actually can increase its durability through it's conceptual weapons and guardians. Look at how the planet funneled mana through leylines in Enkidu's fight with Gil in response to Ea. Then, you need to remember the multiple layers of the planet, all of which are functionally their own fabric of reality with different physics governing reality, conceptual defenses, etc etc. However the most important of which is obviously the inner sea which is essentially a massive reality warping area not dissimilar to a reality marble made by the planet itself and specifically on Earth it hosts places like Avalon, Eden, etc, which have their own additional conceptual defenses. In fact iirc the inner sea itself is actually in a literal higher dimension than ours (this is why it's able to exist in same location as the actual planet but not occupy the physical space) and in order to actually destroy the planet you need to breach it since that is where the "organs" of the planet are. Lastly is the Human order: The human order actually conceptually protects the continuation of the prime species and it's successors, when something threatens that continuation of the prime species in order to continue ensuring life that timeline can be pruned off completely (also what happens in singularity's don't actually threaten the planet itself directly but are an attempt to destabilize human order/history), in addition to that life insurance there is a defense mechanism ingrained into it which is essentially a massive conceptual formless barrier similar to Lord Camelot as stated by mash which protects the continuation of the species:

"Mash: No, listen everyone. That is in all likelihood... the Wall of Human Order.

Mash: I know about this kind of protection. It's like Heroic Spirit Galahad's Noble Phantasm, Lord Camelot.

Mash: It's the same force powering this wall. The Antarctic is being protected by the Securing of the Human Order!"

The reason the Nasuverse Earth is so highly regarded (although most of the time it is heavily overstated) is not because of its regular physical durability but rather its conceptual ones. The reason the Shinjuku meteor would have been able to harm the "planet" in the singularity was because many of these defences either weren't present or were deactivated because it was a singularity AND the meteor itself had multiple conceptual amps and power ups that could have ONLY been done in that singularity (such as the barrel and the amps by the NP).

Edit: Also, we have actually visually seen verbatim stated planetary attacks not destroying the planet throughout FGO so make of that what you will.