Got 10k+ of highly targeted emails, running ads on them?

I got a list of 10k+ emails that are highly targeted and verified, complete with names, Twitter handle, etc. I was thinking of running ads on them but I've been encountering some problems:
-with Google Ads, I tried adding it, only to have it say my target audience is only 300-400 and too low to serve. It does seem to have increased from <100 a day ago, but I'm still confused why the number is so low.
-similarly with Twitter, I gave them 8kish Twitter handles, and it only found 500.
I know my list/formatting is accurate, so 1 issue could be the amount of active vs non-active accounts, or that the people are using their personal email instead.

Either way, other than emailing them, is there a way I could utilize this list? I really want to run a retargeting campaign, but it seems like it's impossible with Google Ads.

Did they subscribe on your site for something specific that you offer or this is a list of scraped emails?
Is they subscribed to you, then, you can do a lot with 10k, if they didn't probably nothing as you will get 10k bounced emails.

They subscribed to a "sister" site of ours, but again, not really looking to do emails vs other forms of ads.

Private emails or business? If first, try FB Ads custom audience

running ads on this email data won't be difficult on fb. you should try running custom audience ads on fb with this list

They're company vs personal email, so unfortunately custom audience wouldn't work.

which country that list from?

Without running ADS, you can setup your own bulk email platform and send quality emails with good offers to your subscribers