Just use the browser dev tools to re-enable text selection? There must be a browser extension that can automate that too. Maybe even Greasemonkey would do.
Go to about:config, and search for dom.event.clipboardevents.enabled and disable it.
The only service I am aware of that it does break is Google Docs, because they handle things in an odd manner. But as they received several bug reports for that since 2017, I wouldn't get your hopes up that it'll ever be fixed.
2. If not, do your parents know how to print to PDF?