"why is it so hard to pedal?"
when you say it has compression, how did you test it, what psi did you get?
i'll second what ☈ℽ∧⋂ posted, but include the entire fuel system.
healthy fuel delivery is essential, and possibly the top no start repair topic.
hard pedalling could be as simple as the decompression not working, i think it's more then that.
if you're not getting good cranking speeds, it won't start.
roll starting is the perferred daily method, easier on everything.
with the plug out, does it pedal smooth? eliminates compression / decomp.
if not, good chance you need to dig into the motor, getting someone that's been there, done that doubles your chances for success.