Is it still not indexed at all now? Even after request indexing on GSC?
I don't know what happens with your site, maybe you just need to wait?
I rarely use new domains, but I bought a new fresh one in Feb (.com promo). Left it idle with empty WP installed.
Last month I schedule 1 post per day, now it has 33 posts published.
I don't submit it on GSC, just let it post 1 post per day.
For 2 weeks, there was no index, and now it only has 1 page indexed. And it's an inner page, not the homepage.
Maybe it will get better indexing if I submit it on GSC and request index. But I am not in rush with this site, so I will keep it this way, for now, to see how Google reacts. I plan to post maybe 50 posts there and see how it goes.
Bing, on the other hand, shows 26 results when I searched site:thatdomain.com
My other new sites (2-3 weeks old), built from expired domains, are indexed properly and quickly on Google. Just for comparison purposes.