Massive shoutout to @Nephryte for being the first (and only until now) victor of this! (minus coins but coins stink)
You can get the game here: gamejolt.com/games/fnacbetter/729972
Getting all enemies made it way worse as I couldn't just skip the mini bosses anymore, other than that not much has changed as Zone 1 and 2 enemies aren't that complicated and I usually went after the them in Zone 3 anyway. Also the fish enemies in Zone 1 don't count as they never stop spawning.
Getting all coins, on the other hand, did not add any difficulty to this run and only made it longer, so for anyone who would want to attempt this run in the future, please, don't go for all coins, it's just a waste of time.
I think my PB before winning was getting to the 3rd mini boss, "I think" because I'm not sure if I got all enemies in that run, I was often forgetting the ones at the start (which is why I started double checking lol).