If you're worried about being unable to extract data from a PC that doesn't have Reflect, consider storing a Reflect installer file in the same folder as your backups. Since you're using File & Folder backups, you'd need a paid version of Reflect rather than the Free version to access these backups, but you could also store your license key as a text file there if it's a device you're securing.
I don't know of a way to do Incremental backups with zip files. Even doing Differential backups would require being able to see the uncompressed size and Date Modified information of the files inside the existing 'Full" zip file, and I've never looked into whether that can be done without actually extracting the zip file itself. But Incremental backups using zip files would be even worse, since you'd have to analyze the contents of all
zip files at the destination, then for each individual contained file, find the newest version that exists in all of your zip files in order to compare that version against the current state of the source. And even if you achieved that, a zip file has no way to indicate that a file was deleted on the source, so the best you could do would be to make sure only new or updated files were created in each new incremental zip file. And even if you were also ok with not having an indication of when something was deleted, performing a full restore would be a pain. You'd have to start by extracting the oldest zip, then extract each newer zip in turn to supplement or replace files that were already extracted from earlier backups -- and again since there was no record of deletions, you'd end up with more files than you might've wanted to have.
In terms of implementing this into Reflect, I seriously doubt it will happen. It would represent a fair amount of engineering and testing work (even minor features requests do), and it would be going toward creating a "mode" that is unable to take advantage of some of Reflect's core existing features, which means I doubt very many people would ever use it. Far more people would likely be confused as to why it was introduced in the first place, not to mention new users not being sure what to choose when they "just want their files backed up". That's not a great value proposition. But this is after all the Wish List section of the forum.
But on a more positive note, below I've attached a modified version of a PowerShell script I wrote a while ago. Just change the extension from TXT to PS1. I've adapted the documentation block at the top of the script according to the modifications I made, so reading that should help you get going and become aware of the areas you'll need to adjust to suit your purposes. You'll essentially be creating Full backups each time you run this. Hopefully this helps!