Grimhook has a good hunk of skips that can be abused. I'll categorize them here.

More will likely be discovered.

Screenwalking: Due to the game's programming, before the first and second cutscenes, your screen fades to black, before it removes your control of the character. This means you can walk for a brief moment after the screen fades to black, and before the cutscene plays.

Tori Skip:

After picking up Kaia-Talia, you want to go to the ravine, where she gives you the ability to tentacle jump. Going past the rock with mushrooms on it will trigger the dialog that unlocks the ability. After that, you want to turn and go back to the first rock you double-jumped on, you're going to double-jump, look at the ground, and then use your tentacle jump.

If done correctly, you will have enough speed and height to get out of the cave and be able to walk right out-side and into the section where you are under the sea wall. After that, you will want to Menu reload to get your abilities

Menu Reloading: Menu reloading is a glitch that allows you to skip unlocking certain abilities such as wall running, tentacle jumping, and double jumping.

This glitch is only possible in one place we know of right now, when you exit the cave and see you are under the sea wall.

Before the hook there is a little wooden box going past it will give you a checkpoint right before the grapple, after which you can go back to the main menu, hit play, and hit continue.

When you reload back into the game the game will give you all the abilities you should have by this point in the game, regardless if you went and unlocked them all.

This skip will save significant time and is very easy to learn.

Slow Hook Skip: If you have killed the robots in combat 1 in the right order the last robot will be on the left of the door, you can hit the robot 6 times instead of 3 to knock it up higher, then you can propel yourself off the robot by pressing space the same way you propel off the lamps.

Doing this correctly will give you enough height to climb the wall on the left and you will be able to immediately go through the Combat 1 gate as soon as it's opened; instead of waiting for the lamp to move and light up. This skip saves around 5-10 seconds.

Watergate/Combat 2 Skip: You can use the lamps that are on before the combat to gain speed which you can maintain with tentacle jumps and with good speed you can tentacle jump before the gate and do the skip as we used to it before a "pacifist* way of doing it was discovered (if this explanation is unclear refer to this run Bisafy's any% no OOB run @ 4:39 in the youtube video).

In Combat 2, you need to kill the first robot, to activate the lamps, after that, you want to grapple to the lamp that is in front of the waterfall and dash off the lamp. To consistently get this trick you want to be looking up and right to the waterfall. To know if you're at the right height - you should be able to see the gap between the wall and the waterfall even if you fail the skip. (this is a slower method that will lose you time compared to the new route)

if done correctly you'll easily get through the gap in the wall and the waterfall.

Best of luck to all of you, speedrunners!