I know the asteroid was real in-universe and that Mothra stopped it. What I asked for was verification that she "stopped it physically", which I took to mean that you were inferring she somehow face-tanked it. The links you provided cleared that misunderstanding up.
As an aside, the type of destruction is never specified. "Destroy the Earth" could easily just refer to a life-wiper like the Chicxulub impactor as the asteroid is termed a "meteor" specifically. For an asteroid to literally explode the Earth a la Alderaan, then it would need to be exceedingly colossal, easily 3x the size of the moon, and traveling at massively hypersonic speeds. At that point, it could be classified as a small planet rather than an asteroid.
SpaceGodzilla was exposed to the energies of exploding stars, yes. This is a well-known fact. It is not, however, synonymous with tanking supernovae explosions. The energy in question is likely a reference to stellar radiation in general, which can extend for hundreds of millions of miles from the star that generates it.
The comics are not canon to the films, so that point is moot. They are still officially licensed media, are based on and expand upon the films, but they exist within their own separate continuities and have no bearing on the films themselves. This is absolutely the case unless otherwise officially stated by Toho.
I'll concede to Toho Kingdom's use of official sources, however the video games are in the same situation as the comics. They're not canon to the movies.
Shin Godzilla is the lowest? I sincerely doubt that. He displayed more destructive power than most other live-action Godzillas, albeit at the expense of durability and stamina. Godzilla's lowest showing is easily the original 1954 Gojira, who only managed to melt/explode tanks and buildings with his atomic ray. Showa Godzilla has destroyed buildings and city blocks, as has Heisei Godzilla (& Burning) as well as the various Millennium Godzillas. It is not baseless, as it is what they're shown to do in the films on numerous occasions. Godzilla's durability, however, has been shown to easily be in the large town to city level. His durability is typically much more impressive than his own offensive capabilities, effectively making him a reverse glass cannon.