  We study the Horizon Wavefunction (HWF) description of a generalized
uncertainty principle inspired metric that admits sub-Planckian black holes,
where the black hole mass $m$ is replaced by $M = m\left( 1 + \frac{\beta}{2}
\frac{M_{\rm Pl}^2}{m^2} \right)$. Considering the case of a wave-packet shaped
by a Gaussian distribution, we compute the HWF and the probability ${\cal
{P}}_{BH}$ that the source is a (quantum) black hole, i.e., that it lies within
its horizon radius. The case $\beta<0$ is qualitatively similar to the standard
Schwarzschild case, and the general shape of ${\cal {P}}_{BH}$ is maintained
when decreasing the free parameter, but shifted to reduce the probability for
the particle to be a black hole accordingly. The probability grows with
increasing mass slowly for more negative $\beta$, and drops to 0 for a minimum
mass value. The scenario differs in significantly for increasing $\beta>0$,
where a minimum in ${\cal {P}}_{BH}$ is encountered, thus meaning that every
particle has some probability of decaying to a black hole. Furthermore, for
sufficiently large $\beta$ we find that every particle is a quantum black hole,
in agreement with the intuitive effect of increasing $\beta$, which creates
larger $M$ and $R_{H}$ terms. This is likely due to a "dimensional reduction"
feature of the model, where the black hole characteristics for sub-Planckian
black holes mimic those in $(1+1)$-dimensions and the horizon size grows as
$R_H \sim M^{-1}$.
