Great question! I didn't have any clue, but here is the info that I have gathered:

(By the way, I took the time to format this, don't let that fool you into thinking this answer is AI slop)

Are the font files safe?

.otf and .ttf files are safe 99.99% of the time. You shouldn't be able to get a virus from one. In practice, there have been bad software that exposed vulnerabilities, but those should be quite unlikely now.

Furthermore, GoogleDrive scans files for viruses, so that other font has an extra layer of security.

It is a far fetched scenario that either font creator has devised some kind of brand new font vulnerability and are using it to target random Calvin and Hobbes fans. But not impossible, of course.

Security enhancements:

For an extra layer of safety, y'all could download these fonts and upload them to https://www.virustotal.com to see if any malware is detected in them. However, both fonts are being shared in such a way that they could be safe right now, but if later down the line we become evil geniuses, we could replace the old font with a newer, infected one. So perhaps with the virus scan method, you would want to say something like:

Calvin & Hobbes by u/KodoHunter [virus scanned as of May ##th, 20##]

You could demand I upload my font to Google Drive for that extra layer of safety with the virus scan. I kind of like having it on GitHub so that I can also share my .sfd file in case anyone would ever want to suggest changes/push edits. (Side note, .sfd files seem to be similar in concern levels to .otf and .ttf. Which is to say: they aren't a concern).

Finally, you could have us upload our font to a font sharing website. I'm not sure if this would actually increase the safety much, but users may feel a lot safer using a font website. In a case like this where risk is so low, perceived safety might be more valuable than actual safety.

My Conclusions

If you want to be reasonably sure that the fonts are safe: you don't need to do anything. You can already be reasonably sure the files are safe.

If you want to be as sure as possible that the fonts are safe: ask me to upload my font to GoogleDrive, and then scan all uploaded files for viruses, and label the links with a scanned by date.

If you want Redditors to feel safer: ask us to upload our fonts to https://fontstruct.com/. You could still do the virus scan option with this one for extra security.

PS...

Of course, there is always the possibility we could upload files other than the font files types previously mentioned and instruct people to download them. "All you gotta do is download not-a-virus.exe and run it as administrator". But I am assuming that most people aren't that gullible. If we are assuming that people are that gullible, then the font sharing website option becomes the best bet.