A bit of a FYI. A proper disco version of v4.0.6 nemo is in our backports ppa.
Likewise a proper disco version of nemo-dropbox is there as well.

Assume this includes nemo-image-converter a bit of a heads-up to get these extensions installed on budgie?

I am not familiar with the image extension in question. On backports we have the dropbox and Nemo-share extensions for 18.04 and later.

When I want to convert an image I just run

convert filename.fromextension filename.toextension


convert filename.png filename.jpg

No, I mean you have a photo of say 1.5Mb which you right click/resize and script changes the filesize its useful for emails and the like. I found a good substitute is converseen which does same job but not integrated to Nemo.