Hi,

Google recommend you use WebP images - instead of jpg, png or other image types.

But, this is not needed to do that. Because Google page speed doesn't reflect your site speed is fast.

Your site speed quite fast for me, it just take 2sec to load everything for me. That's great speed for any website. I don't know why you need to care much about google page speed because as you can see some popular websites in the world doesn't has good page speed score like Youtube ( youtube.com has only 33 score on google page speed - check this image ) or any big news website. The high score on google page speed doesn't make sure your site loading fast.

Currently your site speed is great. I think you don't need to optimize anything more because it doesn't make your site loads faster more or better than on SEO. Just need to feel the site speed is fine for you is ok

Best Regards,

PenciDesign