I wish he hadn’t semi-ghosted me

I agree with the rest of comments but I'll have to say that, I was in a similar situation the other way around. There was a guy clearly interested in me and trying to pursue me years ago and I was very much confused and half-in.

Well honestly we were going for months like that until it just happened and we stick together. I was very confused and feeling incompatible with him.
We ended up staying together for 3 years. He was my best man.

Things had to end and yes there were troubles but I was so happy that it was worth it.

Now, most probably is a situation where he's stringing you along.
And I think the wisest thing for you would be to close the case. ...

At the end of the day, does it matter if he really is still interested? What matters is that you are not happy with the current level of effort and contact from his side and it doesn't sound like he's offered you any firm timescale for when things will improve. So you're in limbo. That is enough for you to decide to walk away, whether he is still interested or not. Sometimes you have to make a stand on what you will accept, because if you don't then you set a very low bar for how you can be treated.

Ditch him. He will only cause you pain.

He wants to see if you'll stick around. He wants to see how bad he can hurt you right from the start so he knows how far he can push you later.

If he cared for you he wouldn't leave you hanging.

This is pretty common for narcissists and selfish men. Please block him and find someone who makes you feel stable.

Feels like he’s stringing you along because he is. People have this way of making time for someone when they’re important to them. Don’t wait for him to decide what course your life will take. Don’t waste any more time. Block him and move on.

Bottom line is
Yes he is stringing you along
Keeping you on the back burner

What really matters is you have a choice to either be strung along or move on ...you don't have to stay in it ...

Ditch him.
He's stringing you along.
If he cared, he'd make time for you.