One way to do what the OP seems to want is to
use a custom tooltip, assigning a shortcut to the "Show item tooltip in a dialog" command.
Example:
- Create a "long text" custom column.

- Set it to show plain text.
- Define a custom tooltip for the column. The template is this:
Code:
program:
f_string('<a href="{globals(original_text)}">link to {globals(original_text)}</a>')
To use it,
- Edit a cell in the column either on the book list or in edit metadata, putting the desired link in the column. In this example I'm using a link to baen.com. It will look something like this:

- Click on the cell.
- Use the shortcut you defined to open the tooltip dialog. You will see something like this:

- Click the link.
If you want to be able to use the link in book details then use a standard long text column containing HTML. Put the link in that. Have the tooltip display the HTML from the column without change because it will already be a URL. Using this technique you can put multiple URLs in the cell. Each will be clickable in the tooltip dialog.