I'll agree with the SIG P365 and Glock holster options being significantly greater than for the PX4, but while I've never shopped for Bersa, Taurus, or Ruger holsters, it would surprise me there would be more options for those than a PX4. However, it may depend on what Bersa/Taurus/Ruger/PX4 models you are talking about.
I have looked at the Beretta website for PX4 holsters and there isn't much I'd pick over other options elsewhere. If you have a particular style of holster you're looking for the PX4, I may be able to offer some suggestions.
Some examples are...
JM Custom Kydex covers the PX4 https://www.jmcustomkydex.com
as does Palmetto Leather Works https://www.palmettoleather.com