An interior architecture degree translates to low man on the totem pole at the architectural firm. You might do interior surfaces specification and some interior design, but it will the scut work the big dogs don't want to do.
Architects will turn up their noses at your architecture "lite" degree and interior designers will think you were snubbing them, not a happy place.
Either commit to the full architecture degree or consider something aligned, such as structural engineering, civil engineering, construction management, urban planning, landscape architecture, or interior design.
Just to be on the safe side, do a little research. Call the school placement office and ask what companies recruit graduates of their program, ask what their average starting salaries are and how long after graduation that they are finding jobs. (Trust me, they will have this info on hand.)
Also ask for a half dozen or so alums who have graduated in the last 3-5 years and get their contact information. Call them and see if the work/salary numbers you got from the school are realistic, what sort of work they are doing, what sort of career ladder they anticipate and whether they have any regrets getting this degree rather than others.