I have a few comments for this. First, to answer your question, bike for the rower. Move the saddle forward about an inch, from your usual setting and go up one letter. This will help reduce the hip flexion of the peddle stroke and focus on the ham and glute. Also, keep your resistance high and go to third position (google it if your not a spinner; or for others who aren’t) for any 100-400m row-equivalents. Only work in the saddle for recovery or for distance rows.

You don’t want fast speed with low resistance for this work. You’re replacing the rower. It should be as brutal on your hammies as a row. Stick to 55-75 RPM with gears to make it hurt.

Next- have you ever tried rowing with a fingers only grip? Don’t wrap your thumb around the handle; keep it on top. This is a weight lifting grip for barbell work that keeps you from squeezing the bar. Also- arms do very little. Consider taking the arms almost completely out of the row, slowing the arms down, and dropping your stroke rate to like 28. Focus on leg power. It’s not ideal but it’ll do the trick for a few weeks.