Linux is just the OS kernel. Most of the standard applications around are not part of Linux but comes from the GNU project, or BSD etc.

And for these tools, you don't normally run into any problems requiring you to consider any source code. They are just as commercial grade as anything else out there. And have a very good support organisation to handle bugs etc.

Next thing is the Linux kernel itself. There are many ports of Linux. Red Hat is not really big on embedded. Many companies specializes in Linux kernel releases specifically for different target processors. And they do sell support for implementing new hw drivers (or normally to help port existing drivers that haven't joined the mainline source).

When people do talk about open-software projects, it's normally not anything directly related to Linux or BSD but applications that happens to be written to run on an Unix-compatible OS. Sometimes by someone who haven't access to many of the architectures supported by Linux, so with lacking support for little-endian or big-endian or 64-bit processors etc. But they would have problems even if they did work on an application for Windows targets - the application isn't better than the resources available to the developer(s). So commercial applications from smaller companies (or from smaller subdivisions of larger companies) often have the same kind of issues. Just that the commercial releases often guarantee that when you are stuck you are really stuck.

In the end, a company should avoid any route where own competence doesn't exist. It's better to buy from someone with the required competence than to take a chance. Same for use of commercial or open-source products.