Do I need a foldable or compact rower for an apartment?

If floor space is limited, yes — but note that even the Concept2 RowErg separates into two pieces and stands upright for storage. Reviewers of the Merach R28 and Sunny Health foldables highlight true fold-flat designs at the cost of shorter rails, which taller users (over ~6'2") on r/Rowing say can cut the drive short.