Can we detect evaporating micro black holes? The energy released by an evaporating black hole in its last instants (of duration $t$) is equal to
$$E = \sqrt[3]{\frac{t \hbar c^{10}}{ 5120 \pi G^2}}$$
As the math shows, most of the black hole's life will be quite boring, but in the last second 2.051288979×10²² J of energy will be released. That's more or less 1000 times the total nuclear arsenal of all the nations on Earth.
It might sound like a lot, but on a cosmic scale it is actually very tiny. Our sun in one second produces about 3.8×10²⁶ J of energy. Seen from far, the final instant of an evaporating black hole will look like a dim light, 18 500 fainter than our sun (the wavelength of the electromagnetic radiation produced will differ too).
Can our telescopes detect such sparse dim lights? How far can we go? Can we see them in other galaxies?
 A: For supernovae, the appropriate energy scale is one foe${}\rm = 10^{51}\,erg = 10^{44}\,J$.  You are correct that $10^{22}\rm\,J$ is a lot of energy on a human scale. But a supernova is different from that by a factor of approximately $\rm1\,mole \approx 10^{23}$.  The luminosity of a black hole is strongly peaked at the very end of its life; a black hole is not bright for a mole of seconds, so black-hole evaporations are less bright than supernovae.
According to this nice calculator, a black hole with mass $M$ has
\begin{align}
\text{lifetime } t &= \alpha M^3
\\
\text{luminosity } L &= \beta M^{-2}
\end{align}
If we start our computation when the black hole has the same luminosity as the Sun, its remaining lifetime is about forty nanoseconds. The mass converted to Hawking radiation in those final nanoseconds is only about $1000\,\mathrm{kg} \approx 10^{20}\,\mathrm J/c^2$; before this time the hole’s total brightness is less than the Sun’s.
Most of the actual light from a supernova (which is bright for months) comes from the interaction between the supernova’s released energy and the medium which surrounds it (much of which began as the outer envelope of the progenitor star). The famous Type Ia supernovae get brighter over several days or weeks as radionuclides produced in the explosion decay. In terms of total energy, an evaporating black hole is nothing at all like this.
However, in the far-field region, most of the energy released by Hawking evaporation is electromagnetic, and the peak photon energy goes like $E = {hc}/{\lambda_\text{peak}} \propto M^{-1}$.
A “typical” Hawking photon has energy $E>1\,\mathrm{GeV}$ for the hole’s final $10^8\rm\,years$; during the final moments, typical photon energies are unreasonably large.  High-energy photons can interact with the interstellar medium by making particle-antiparticle pairs; the antiparticles can then annihilate on matter in the interstellar medium, eventually making lower-energy photons whose momentum is still directed mostly away from the source. (For that matter, the near-field Hawking radiation from a sufficiently-warm black hole will also include particle-antiparticle pairs directly; only the neutral components of this radiation will get very far.)
And we do have the only-partially-explained phenomenon of gamma-ray bursts. One goal for gamma-ray telescopes is to identify possible black hole evaporation events; none has so far been reported. I’m sure there is a literature which speculates about the volume over which such events could be detected.
