Probably some random non-Abrahamic countries in Asia could do so - Bhutan, Mongolia, Philippines, Singapore? I wouldn’t bet on any, but there’s a possibility.
One other left field one could be Namibia. The Supreme Court there recently ordered the government to recognise gay marriages performed abroad, and a case to decriminalise sodomy is due to have the judgement announced on the International Day Against Homophobia, which seems a none too subtle steer on the outcome. Obviously it seems a bit odd to suggest a country where homosexuality still isn’t legal, but the court is clearly quite activist on this issue.
Some random country in Eastern Europe could also be possible I suppose.
The Philippines is supermajority Christian and Singapore has large Christian and Muslim minorities.
As far as Pacific-facing Asia is concerned I think Taiwan will be the only country
for at least the rest of this decade. Thailand is probably next most likely to legalize SSM, but I’m not sure how the elites of those countries would feel about that possibly unwittingly reinforcing Anglophone observers getting the two countries mixed up.
