I have a CRS309-1G-8S+ and CRS305-1G-4S+ both have SwOS 2.13 from Apr 26, 2021. Is there a newer version? The switch says there are no updates. I don't even see a download option for these devices on the product pages.

What is the latest and is there an way to download and manually upgrade? Hard to believe version 2.13 is almost two years old with no update since then. Have these devices been abandoned?

Unfortunately, version 2.13 is still the latest SwOS version officially available.

Not in the product pages, but downloads are here: https://mikrotik.com/download
Lowest 2 entries on this page.
Indeed only 2.13 for most devices.