I just got into megaminx very recently so I average about 1:35. I'm not sure of a place to to grind megaminx PLL but a quick web search showed me this: https://nogesma.github.io/megapll-trainer/ which I think looks very nice.
I worked on my LSLL lastnight and I can complete it in around 16 on average but every now and then I'll get some hard to recognize cases and it can take over 20 seconds so if I can fix that I can sub-15 my LSLL easily. It's a very fun puzzle and I currently main the Dayan v2m but next time I order from TC I'm going to pick up an Ambition 4x4 and a Galaxy V2 LM.