FWIW, on my shared host with cPanel, I've even installed XS-based modules via cPanel. At one point, they upgraded perl (thus obsoleting the compiled modules I had already installed) and disabled gcc access; but one trouble-ticket later, and it was re-enabled, and cPanel would let me install those modules again. So cPanel itself isn't enough of a hurdle to prevent installing pure-Perl or even XS modules. But yes, some hosts who use cPanel might not be so friendly and allow you to install XS modules

And even outside of cPanel's interface: since you can use lib ... in your script, you can upload Pure-Perl modules someplace in your user hierarchy, and direct your script to load modules from there.