Let $N = q^k n^2$ be an odd perfect number given in Eulerian form, i.e. $q$ is the special/Euler prime satisfying $q \equiv k \equiv 1 \pmod 4$ and $\gcd(q,n)=1$. In what follows, we denote the abundancy index of $x \in \mathbb{N}$ by $I(x)=\sigma(x)/x$, where $\sigma(x)$ is the sum of the divisors of $x$.
In Case 1 under Remark 3.1 on page 4 of Basak's Bounds On Factors Of Odd Perfect Numbers, it is proven that
$$\frac{16}{7\zeta(3)} < \frac{16q^3}{7\zeta(3)(q^3 - 1)} < \bigg(1 + \frac{1}{q}\bigg)\prod_{p \mid n, \hspace{0.05in} p \neq q}\bigg(1 + \frac{1}{p} + \frac{1}{p^2}\bigg).$$
But we also have $$\bigg(1 + \frac{1}{q}\bigg)\prod_{p \mid n, \hspace{0.05in} p \neq q}\bigg(1 + \frac{1}{p} + \frac{1}{p^2}\bigg) < I(q)I(n^2) \leq \frac{6I(n^2)}{5},$$ since $q$ is prime with $q \equiv 1 \pmod 4$ implies that $q \geq 5$.
(Note that this last inequality is unconditional on the truth of the Descartes-Frenicle-Sorli Conjecture that $k=1$.)
This implies that $$\frac{16}{7\zeta(3)} < \frac{6I(n^2)}{5}$$ from which it follows that $$I(n^2) > \frac{5}{6}\cdot\frac{16}{7\zeta(3)} = \frac{40}{21\zeta(3)} \approx 1.58458547158229994034881195966.$$
But then this resulting numerical lower bound for $I(n^2)$ is trivial, as it is known that $$I(q^k) < \frac{q}{q - 1} \leq \frac{5}{4} < \frac{8}{5} \leq \frac{2(q - 1)}{q} < I(n^2),$$ so that we already know, unconditionally, that $I(n^2) > 1.6$.
Here is my question:
Would it be possible to tweak Basak's argument in order to come up with an improved lower bound for $$\bigg(1 + \frac{1}{q}\bigg)\prod_{p \mid n, \hspace{0.05in} p \neq q}\bigg(1 + \frac{1}{p} + \frac{1}{p^2}\bigg)?$$
Update (May 1, 2020 - 13:45 PM Manila time)
I re-read Basak's argument in Case 1 under Remark 3.1 on page 4 of the hyperlinked paper in arXiv, it appears that Basak does make use of the assumption that $k=1$.
We get $$\frac{16q^3}{7\zeta(3)(q^3 - 1)} < I(q)I(n^2)$$ from which we have
$$I(n^2)\gt\frac{16}{7\zeta(3)}f(q)$$ where $$f(q)=\frac{q^4}{(q^3-1)(q+1)}$$
Now, we have, for $q\ge 5$, $$f'(q)=\frac{ q^3 (q(q^2-3)-4)}{(q + 1)^2 (q^3 - 1)^2}\gt 0$$ from which we have
$$I(n^2)\gt\frac{16}{7\zeta(3)}f(q)\ge \frac{16}{7\zeta(3)}f(5)=\frac{1250}{651\zeta(3)}\approx 1.597364$$ which is better than $1.584585$, but still smaller than $1.6$.