For a concrete example, have a look at SQLite. SQLite is Public Domain, but it's used virtually everywhere, from phones to airplanes (https://www.sqlite.org/famous.html).

Not all companies are going to trust that something is actually public domain. So, you can get a "Warranty of Title" for SQLite. See https://sqlite.org/copyright.html

And those companies might not be satisfied with "community support". So, you can get paid support for SQLite. See https://sqlite.org/prosupport.html