Yes, a posts parent_id is the ID of the parent post. There is no restriction on the type of post linked to, so from a data point of view, yes you can do this, and it has been done elsewhere, but it isn’t common.
From a UI and URL point of view though, you will need to do work. You will need to build the selection UI. Luckily it can take the same format and input names as the existing UI, but when building you would supply different options to the control and render it yourself, rather than using a helper function or the existing control. You’d do this the same was as any other drop down box in a custom metabox, save for the name of the dropdown input. Note that plugins such as ACF will not help you here unless specifically built to do this.
For the URLs, you’ll need to write some custom URL rewrite rules. The hard part is getting a regular expression for the URL you want to match against that works. You will also need to filter the permalinks of these guide posts so that they contain the correct full URL rather than the shorter direct URL without the parent guide.