Not exactly, the product is still really young and we are growing the feature-set with each release, the feature you mentioned is coming a bit later in one of the upcoming updates. Important note, there will be no paid version of MSP360 Explorer for macOS all the features are available for free, forever.

Any estimate for "a bit later" ?
I do think it's great that you have Mac support in the works.
Previously we were using S3 Organizer add-on for Firefox on Mac to upload files. It was able to set the Content-Type automatically. This worked on Mac as long as one stayed with a very old version 18 of Firefox.
Suddenly the S3 Organizer add-on stopped working. I guess one of the security protocols finally expired on the AWS side.
That leaves us in a bind, looking for an upload tool for a non-profit personal web site that my uncle maintains.
If your release will be soon, before 15 July, we'll wait. Otherwise I will need to script something on the AWS side to adjust the content type after the files arrive.
I thought possibly the "Upload Rules" feature in the 360 product was meant to handle this.
Advice welcome.

FWIW I have coded a workaround for this for my uncle for the time being.

It would be extremely helpful to know a rough release schedule. Days? Weeks? Months? to next release? Is there a road-map available?

Sorry to bump this topic.. but is there now a setting to adjust the content-type? Whenever I push an HTML file or even a CSS file, the browser tries to download the file when you go to the URL.

I do not think this feature has been added to the Mac version of Explorer. At this point, given the age of this post, I would not feel comfortable telling you the feature is coming. You can either move to the Windows version of Explorer. Or, if you're dealing with a small number of objects, you can change the content-type in the Amazon S3 Management Console. Wish I had better news. I'll log your request in the system.