This is a solved problem with Safari since at least High Sierra days. You add any webpage to your reading list and with appropriate settings you'll have a full local copy.

https://support.apple.com/guide/safari/keep-a-reading-list-s... relevant quote below...

Save a page in your Reading List to read when you’re not connected to the Internet: Control-click the page summary in the sidebar, then choose Save Offline. You can also swipe left over the page summary, then click Save Offline. To automatically save all pages in your Reading List, choose Safari > Preferences, click Advanced, then select “Save articles for offline reading automatically.”