The first time I played, I beat it with 262 seconds left. I then went back and tried a few more times and ended up with 372 seconds left. Everyone's already suggested making the shop "on the fly" instead of a physical shop menu you have to open, and someone already pointed out the lack of sound, so I won't talk about either of those. My main points of feedback are:
1. A single sprint can carry you as long as you hold down the shift button, which makes it slightly overpowered since you can essentially pay 1 or 2 seconds to knock a huge percentage of your time off. If you want sprinting to be reserved for hard platforming sections, I'd suggest putting a time cap on it (again, this is where the "on the fly" system would shine).
2. Looking around itself costs time, so while the longer paths may have been shorter time wise, I feel like going "off path" is almost never worth it unless you're speedrunning and you already know which paths to take (source: me, who sorta did try speedrunning). If you want to encourage the player to strategize more, you could do something like allowing the player to scout out the path ahead of time. Note that this would turn the game into more of a puzzle platformer than an action platformer, which may be good or not depending on what you're going for.
Anyway, congratulations on your two month milestone!