Generally speaking, you cannot have a health FSA and HSA at the same time. However, there are a couple of exceptions: limited purpose FSAs and dependent care FSAs.
for the months married as long as you have a FSA (for medical) (which by law covers your spouse) he can not contribute to an HSA because the FSA is considered disqualifying coverage
assuming he had self-only coverage and is under 55 the max he can contribute for 2022
is 10/12 of $3650 or $3042. this can be a combination of payroll deduction, employer match or direct contributions. overfunding not withdrawn by the due date of the return is subject to penalties.
nothing I've read specifically covers an unfunded FSA and HSA. however, the rule says you can't contribute to an HSA if you (or your spouse) are covered by any non-HDHP which is what an FSA covering medical expenses is considered. apparently, you have money left in the FSA so this is a moot point.
the plans year do not matter.
