Hubble sphere is the limit of seeing objects from Earth. But if it wasn't like that would it be possible to see a supernova just because of luminosity over that distance. In simple words would a distance so large make the supernova light too weak to be seen from Earth?
The limit is set not by our ability to detect supernova, but by when the first stars appeared.
The most distant supernova observed, SN 1000+0216 (Cooke et al. 2012), had a redshift of $z \simeq 3.9$, corresponding to a distance modulus of $\mu = 47.8$ (note that it also corresponds to a distance of 23.7 Glyr, well outside the Hubble radius of 14.4 Glyr).
It was a superluminous supernova reaching a peak absolute magnitude of $M = -21.5$, so the apparent magnitude was $$ m = \mu + M = 26.3. $$
The first stars in the Universe emerged around redshift $z\sim20$, roughly 180 million years after the Big Bang (Bowman et al. 2018). If a similar supernova goes off at this redshift, its apparent magnitude would be $m = 30.3$, which would be observable with Hubble (albeit on the border). Future JWST will reach even higher limiting magnitudes. Moreover, gravitational lensing can magnify events in some cases by a factor of 1000 or more, so in principle we should be able to see the first stars explode.