Looking at the Pennsylvania license board, I noticed this in the FAQs:

"The Architecture Licensure Law does not prohibit the preparation of any drawings or other design documents for dettached one family or two fmaily dwellings not more than 3 stories in height and their accesory structures."

I'm an Architect, but from another country, does this means that I can offer architecture or interior design services without a state license?

Of course, Im talking about small stuff, renovations, interior design, etc...lets say even a small vacation house.

Not sure, but my engineering firm sometimes stamps drawings that are going to permit for architects who arent licensed. I believe when getting a building permit it is required to have either a licensed architect's or engineer's stamp on the drawings.

I believe anyone can prepare the drawings for the stated size dwellings, you just need the stamp.

I have no idea about Interior Design.