You need to get down under the firewall and see what's there.
On the Wrangler, drilling from the inside toward out, there really wasn't anything behind the interior firewall that could be damaged.
The engine compartment will probably have a thin heat reflector, sort of like foil covered cardboard.
Screws coming through the firewall (from the interior) simply pushed the foil reflector up a little bit - no harm.
A tip on mounting the pulley (if you go that route) is to use a 1/8-inch x 18-inch drill bit. The longer length bit allows one to stand-off with the screw gun for better placement and accuracy.
2021 Arctic Fox 1150
'15 F350 6.7 diesel dually long bed
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Yeats