No the 3a cannot be used via officially supported install methods.

You would be required to build it yourself, look for the last release tag where pixel 3a was supported and continue on from there.

The 3a is also not a very good device to even get a taste of the OS as the 3rd Gen Pixels eMMC memory is terrible and a handicap for doing so.

Minimum supported device advisable is a Pixel 5.

However a 6a or 7a would probably be the most cost effective and provide a better resale option if not happy for whatevwr reason.