Is it possible to produce sulfuric acid at large scale by oxidizing and hydrating pyrite?
Per a source, there is an iron bacteria path acting on FeS2 to create sulfuric acid:

Thiobacillus spp. are participants of active oxidative corrosion. They oxidize a range of sulfur compounds to sulfuric acid, and the acid released from the cells may attack alloys.

My experience, however, suggests that the easiest way to produce H2SO4 is by the action of a concentrated solution of Oxalic acid (used in commercial products) on magnesium sulfate (FeSO4 may also work, but likely leads to an iron impurity).
Per a source (old Wikipedia commentary) to quote:

Relationship to oxalic acid
The dissociation of protons from oxalic acid proceeds in a stepwise manner as for other polyprotic acids. Loss of a single proton results in the monovalent hydrogenoxalate anion HC2O4−. A salt with this anion is sometimes called an acid oxalate, monobasic oxalate, or hydrogen oxalate.&quot;

As such expected reactions:
$\ce{MgSO4 + 2 H2C2O4 -&gt; Mg(HC2O4)2 + H2SO4}$
$\ce{MgSO4 + Mg(HC2O4)2 -&gt; 2 MgC2O4 (s) + H2SO4}$
Be careful, the created Sulfuric acid could be very strong depending on the level of hydration.
Warning: Attempting (in the presence of H2C2O4) to produce fuming sulfuric by boiling down the solution can lead to a spontaneous ejection of the acid (reported in an old thread of mine).