The developer has stated that support for GM API is not planned, and yet, because the summary of FREE Browser does mention "Greasemonkey style script support", I think it would be worthwhile to make attempts adhering for GM API support for FREE Browser.

Re: @sjehuda:

Did you try it yet?

Skimmed over the code a bit. Seems to be a static copy of blink (i.e. Chromium V8 engine). Which makes it fall under the same category warning of Tampermonkey for Android where it can be out of date rather quickly.

does mention "Greasemonkey style script support"

That would be consistent. It does partially support a UserScript metadata block. The missing items that it doesn't include are disappointing including the non-existent @required scattered in the repo and some other useful/critical ones, excluding @include of course. Major typo perhaps.

The repo seems to be a very new to Userscripts and imho needs some more work before it should be considered as viable and safer.

I realize that you are excited to share this new to you found app however this came very close to triggering a spam action. Please curtail your enthusiasm from sounding like a cheap car commercial... especially in the Discussion title (and no it won't be changed).