

As a Pagan, if you want federal holidays to be secular then solstices and equinoxes couldn’t be counted. Many Pagans (not all) observe them as holy days along with Feb 1-2 (Imbolc), May 1 (Bealtaine - there are multiple spellings this one), August 1 (Lammas/Lughnasadh), and Halloween (Samhain). And I’m sure Pagans that celebrate non-European traditions have other days, I just can’t speak to them personally.
Secular refers to things not religious or spiritual. Those days are religious holidays in various forms of Paganism which is an umbrella term for a set of religions/spiritual practices. If anybody wants truly secular holidays the equinoxes and solstices shouldn’t be included in that list.
(Edited to fix typo)