I do the same thing. Since I'm a serial holster shopper, before I buy a somewhat odd gun, I always look for holster options. This is often exacerbated by the fact that many holster makers either don't have a "guns supported" list, or don't update it very often.
A couple holster makers I've checked for odd-ball guns in the past, PJ Holsters (
https://pjholster.com/p/gun-models-available ), and High Noon Holsters (
https://highnoonholsters.com/ ) don't show that gun on their list.
The other problem with that particular gun is figuring out a cross reference for it. Tanfoglio is not common in the US, but EAA carried many of those guns under their Witness name. I don't follow EAA very closely, but it looks like they may have pared down their Witness guns.
https://eaacorp.com/
Another option you'll often find is holsters sold by the gun maker. Kahr, Kimber, and Ruger, often have holsters for sale in their on-line store. These are usually from known makers, so the gun maker shows some style of holster, but it's not what you want, you can go to the holster maker with the understanding that they have a mold for that gun, and they can probably make a different holster for your gun. Unfortunately, it doesn't seem as if Tanfoglio sells holsters off their site.
https://www.italianfirearmsgroup.com/ftitalia/
Another option, since Tanfoglio is a Euro Company, there may be some Euro holster makers that have holsters available in the US that support that gun model. Falco (
https://www.falcoholsters.com/ ) is one, they have a US distributor that several folks have holsters from, but the US Company name doesn't come to me right now.
Edit to add: Just as a point of reference, I've avoided even common guns like the Beretta 92 family since there are so many differences with the guns, such as straight/slanted dust cover, round/square trigger guards, railed/non-railed, standard/Vertec/Brigadier slides, etc., that figuring out what holsters would work with almost anything other than a standard M9/92FS is still somewhat of a mystery. Instead, I still picked a somewhat odd gun, the PX4, but it is a full size 9mm, and all full size 9mm PX4's are the same - rail, trigger guard, slide, etc. It's not a terribly common gun, but there aren't many differences within the model lineup.