Unfortunately, no… Someone had asked this question before and the devs said it wasn’t possible, since you need the input files to properly remake your site (since all of your posts are stored on a database in the input folder).
At best, you might be able to save a copy of your stylesheet if your website is online and use that, if you made any extensive styling.
Here are some other posts on the topic:
https://github.com/GetPublii/Publii/issues/1028
Help me restore my sites after I stupidly erased some stuff!
