Please start using the excluded tags from steam

Short answer: Yes, this can work in scripts.

Long answer (and if there's anything I'm mistaken about, I'm always appreciative of well-considered corrections):

Steam has two access points for its API. A developer access point [which is also used by websites, and can only access publically accessible information], and a user access point [which is used by Steam Community, or anything else you actively need to log into Steam Community for].

Technically SG could presumably also implement a layer to the website's design which utilizes the private access point, but it'd be a whole layer of development that'd only benefit users who are actively logged into the site (personally, I'm rather appreciative of the fact that I've never had to relog into Steamgifts after first joining it back in 2015:P). Unlike many other long-awaited site features, this one seems likely to be more of a pain than it's worth to implement, relative to the somewhat lower amount of effort it'd take to implement the matter through scripts.

Meanwhile, scripts won't have direct access to the developer side, but can check private information available within your browser- that is to say, it can access your private Steam Community information if you're logged into Steam Community within that browser. Thus, you still won't benefit from this feature if your Steam Community login expires, but otherwise it does mean that your private information would be accessible [or at least, whatever private information Valve has configured to be available to the API- ignore tags, for example, require manual loading, and it's my understanding that's because they're not set up through the API].

Further, any expanded functions that would potentially make use of such tags would be run through scripts as well, so there's that additional merit to having the tags be run through scripts.

What I mean is, you are asking for something that first need something else that Steamgifts doesn't even has so if you want this, the first request would be for Steamgifts to add tags since without those, your request is meaningless.

Like LittleFreak above me said, it's better and faster to just ask ESGST or whatever if they can add it since they already use tags and such stuff already anyway.