Are there any Bitcoin block explorers still around that log First Seen by node data?
Could you be a bit more specific?
There are a few block explorers that do provide information specific to their block explorer's running node.
Best lead I have for you is: https://bitcoinvisuals.com/
There's a lot of node information on there though I'm not sure its exactly what you're looking for.
However, I know that the owner of the site is pretty responsive and very easy to get into contact with.