does changing oil and filter on ecoboost 1.0 give an indication of wet drive belt condition 

Unfortunately, no

Well, I suppose you could drain the oil through a sieve and see if there's any debris in the sump.

But the debris mainly gets sucked up into the oil pick up gauze  

If you drain the Oil through a very fine sieve then you should see if any bits have broken off. It won't tell you if they are about to drop off though.

Just now, Tizer said:

If you drain the Oil through a very fine sieve then you should see if any bits have broken off. It won't tell you if they are about to drop off though.

Great minds think alike👍

When they're really bad you can see bits of belt colouring the oil, it looks jet black like diesel oil.  Though I wouldn't trust cleanish oil to mean the belt is ok.

19 minutes ago, DaveT70 said:

But the debris mainly gets sucked up into the oil pick up gauze  

And some of it is very fine, even translucent, not all black and obvious based on the one I cleared a few times.

Not sure what car you have (so far you've posted in C-Max and now Fiesta forums) but if it's a 2014 1.0 ecoboost the belt is due for changing.

We've had several posters who've had them go literally days before a booked appointment and plenty that haven't made it this far.