Could filler fix my gummy and crooked smile or would I need a Botox lip flip? (photos)

Hi there. It might be worth trying a lip flip first as the results only last roughly 2 months. The product wears off faster here than higher areas of the face (3-4 months) due to the frequency and intensity of movement of the muscles around the mouth which help us to talk and chew. So if you don't love the results, it will have worn off quickly and you could then consider a small amount of lip filler to your upper lip border.
Also a small amount of neurotoxin (botox) could be placed to relax the muscle on either side of your upper lip to lower it slightly when you smile. The risk of this is asymmetry to your smile but if you find a experienced medical practitioner the risk should be small.

Thanks and take care.

Botox can be used to lessen the appearance of a gummy smile. It will cause the upper lip to cover more of the teeth. A lip flip will cause more of the "pink part" of the lip to show. The results last typically three to four months. See an expert injector near you to learn more.

Great questions!
You have a very pretty smile, which could be enhanced, in my opinion, with appropriately injected filler. My favorite hyaluronic filler for lips is Kysse, which could (temporarily) make your "gummy smile" less gummy, and increase the vertical height of your lips to reduce the local areas of thinning seen when you smile. If you liked that, you could consider having them injected with Silikon 1000, using the micro-droplet technique.
Using neurotoxins (like Botox, Xeomin, and Jeuveau) to treat the gummy smile involves targetting different muscles around the lips than the lip flip....so if you go that route, I highly recommend you go to a very, very experienced neurotoxin injector. (Like you mention, I have seen some pretty awful results from inexperienced injectors, which affect the person's ability to clearly enunciate or whistle or suck on a straw.)
The best of luck to you!