How can you tell if a DA is trying really hard?

Booty Call.
No DA i know will only make effort for sex if they desire a connection.
Every DA i know will make an effort at emotional connection if they want an emotional connection.
Some DA i know will make an effort for emotional connection to a limited degree even if they only want a booty call.
It depends on the person. it depends on the situation.

I remember you writing that your Ex DA told you point blank he could not give you what you want in a relationship.
and he respected your wishes and boundaries and was very honest with you about his limitations and what he was interested in.
The fact that you are still questioning this points to your own issues. you would find peace more quickly if you examine why you are analyzing his behavior in spite of his providing clarity for you.

i don't know what has happened in the meantime between that other post i am referencing, and now.

But if a DA wants a deepening emotional connection with you, you will know it.
whether or not that connection is enough , and backed up by commitment and long term intentions can sometimes be determined more through the use of common sense than attachment theory, frankly.

Often, people use attachment theory to try to analyze and find a way around pure emotional unavailabilty.
As if understanding and catering to dysfunctional relating habits can form and support true intimacy. i'm not accusing you of that. but it happens a lot here.

That's not how it works. Understanding avoidance and compensating for it doesn't create intimacy or relationship, it creates personal inpingement and compensation. that's all it creates. It destroys more in the compensating party than it creates in the relationship.

A person (both parties!) must address their internal blocks to intimacy and improve dysfunctional relating habits in order to forge intimacy. It's a dual effort, and one that must be agreed upon mutually, instead of one person jumping in the drivers seat to make all the requests and accommodations for both parties.

A mutually agreed upon, openly communicated joint venture is much more likely to be a real connection than a one-sided guessing game where needs, intentions, feelings, and behaviors are all subject to interpretation.