I'm lacking details from your wish of course, but if you need to run several, disparate different software....Could not one of the common linux distros like Ubuntu, Redhat/Fedora, SUSE, etc. suffice, and of course have a powerful enough machine to run virtual machines or maybe WINE? Obviously this depends on whether you were asking for client side or server side...And if on the client side, things - as you know very well - can get very tricky because you then have to deal with training and general acceptance.

When i used to have my IT side hustle company, whenever i supported software for small businesses, i often found that nuding them to web equivalent software made things alot easier. For example, some users get comfy with software faster when its within context of a web browser...Of course, this is different for every user/org and with different software, it depends. But it lessens your support away from conventuional desktop supporot. However, if the web softeware is managed hosted then its much easier, but if you have to manage the hosting, then you would need web management sort of skills. for me that was my forte, so it was easy for me.

As to your wish to find a linux distro for business tech, there are platforms like Odoo (see wikipedia: https://en.wikipedia.org/wiki/Odoo)...but they're not lightweight, and back to my earlier point, you'd have to build up your skills administrering web apps, server, etc. I'm sure there are plenty of other options beyond Odoo. Try a couple of searches against odoo; the old google hack of "odoo vs..."

Good luck!

EDIT: Sorry, i meant to direct my comments aboive to @importgravity :-)