Did you ask in the theme support forum?
[Frost] Support | ww.wp.xz.cn
Can you just add the call to the Google Font using their CDN in the header.php file of your theme?
How To Add Google Fonts To WordPress | Name Hero Help Center
WordPress 6.5+ has native support for Google Fonts out of the box (when using any block theme), with no need to install any plugin(s) or custom coding.
1) Navigate to APPEARANCE => EDITOR => STYLES.
2) Click the pencil icon to open the Style Book, and select Typography: https://s3.amazonaws.com/i.snag.gy/5goFjw.jpg
3) Next, click FONTS settings icon to open the Fonts manager: https://s3.amazonaws.com/i.snag.gy/i2Umge.jpg
From here, you’ll see existing fonts. You can also upload custom fonts, and allow your site to connect to Google’s servers to install Google Fonts (this is OPT-IN likely due to privacy and legal concerns).

Nice one @gappiah ! I didn’t know this! 🙂
Sorry for the late answer, I am in Italy and we are not properly sunc’ed as far as the time is concerned.
Thanks for your interest. The procedure suggested by @gappiah is the one I tried in 2), and unfortunately I have to confirm it does not work in Frost, whereas it seems to work , for example, in twenty-twentythree. So what proposed by @corrinarusso of asking the question to the Frost support seems the way to go. I chose Frost because it was simpler, so more suitable for experimenting, but apparently I was wrong.
Thank again for your help
and unfortunately I have to confirm it does not work in Frost,
It should… it certainly worked for me.
The first thing I do before answering most questions is to try to replicate the user’s environment. So I installed and activated the Frost theme before taking the screenshots I provided.
You may create an instant test site at TasteWP.com (no sign up required) to test this. I just did this (for the second time), and yes, the feature is available when using the Frost theme.
But note that, as I mentioned in my first post, this is a WordPress 6.5+ feature. If you’re testing this on the site in your forum profile, that’s a 6.3 site!
As I said, I am experimenting with block theme. The site in my profile is the “public” one, is an old implementation and uses a classic theme (tesseract). To experiment, I am using the free hosting at infinity.com, and it was my intention to try to move that public site to a block theme. In this test environment I am using WP 6.5.2 and Frost theme. Since it works in your test, maybe in my case there is some incompatbility with one or more plugins. PLease don’ forget I am really a roookie trying to learn…
https://drive.google.com/file/d/1FYj8fz-G6VKh0Uw1vpThoSzloXiCRX46/view?usp=sharing
https://drive.google.com/file/d/1lwB45ldR7JjykieP4ltlo1aCP8bWBasG/view?usp=sharing
Loading google fonts still does not work in Frost. I disabled all plugins, just to be sure, and still no “load gooogle fonts”. I also tried on a different installation (local server, using Laragon), same result. I posted a request in Frost support forum, no answer at all after five days. I really don’t understand what is happening here,
I went through the trouble to install Laragon, setup a fresh WordPress site (6.5.3), and installed the latest Frost theme (1.0.9).
And I CAN see the “Upload” and “Install Font” tabs, both of which are missing from the screenshot you provided above). Here’s a video of my screen: https://vimeo.com/944177895
One thing I noticed (which you can see from my video) is that it took a second or so before the “Upload” and “Install Font” tabs appeared. So I’m wondering if something in your local environment (browser extension, computer, network, etc) could be blocking these two elements? I know it’s a wild thought… but I really can’t think of any other reason. Can you check your browser’s developer console to see if there are any errors?
Thanks for your answer. Unfortunately, I am not able to understand the output of the browser develoment console, what I can see is a bunch of errors…hope you can figure something out of it.
https://drive.google.com/file/d/1NezI_ceXTlWuhvoqTqMvyclvGnrCdeAR/view?usp=sharing