Yes they are manufactured in house according their youtube channel.
https://youtu.be/KXZ7oXT3wak

Melissa, Fusion manufactures all their firearms in their FL facility. - From Fusion web site "The Fusion Firearms Liberty Series is a fully supported shotgun line, with a full warranty, in house service and repair, and a full line of replacement parts and accessories.
Fusion has factory trained gunsmiths in house that will service, repair or upgrade any shotgun in our line. We stand behind every one of our shotguns and are one of the very few with this level of customer service. Fusion Firearms has a legacy of providing a great firearm backed up by superior customer service. We intend on keeping that reputation going with our Liberty Series."

Melissa, these are 100% made in their Florida facility. Cheers and stay safe!

Yes they are all made in house good video, by the founder on their youtube channel.
https://youtu.be/KXZ7oXT3wak