GIFs have a lot more capabilities than any current software allows for (some software has had such capabilities but updates changed that). For example, it can be used to store images with more than 256 colours by splitting it up into different anination frames for different colours, giving each frame a different colour palette rather than using a global one. I don't know why you'd want to do this as it would be rather large in terms of file size, but it's possible.
You could, however, embed an animated GIF within an SVG which could also consist of a JPEG or PNG, which would allow you to, say, have part of your image animated while maintaining more colours and possibly lower file size. I say "possibly" because the GIF and JPEG/PNG would have to be encoded in base64 if the SVG were to be embedded on an external site such as TBT, which would result in a file size increase for them. But perhaps it would be worth it. I don't know.
There are also quite a few ways of achieving animation, from each frame replacing the previous to combining frames, as well as good ways of optimising GIFs for size due to the fact that they use LZW compression by doing things such as extending colours horizontally (GIMP can do this).
The delay between frames can only be multiples of 10 milliseconds, so you'd have to settle for something such as 25fps, unless some frames have a longer duration than others in order to achieve a different overall frame rate, although it's worth noting that most browsers and image viewers dislike frames with a duration of 10 of 0 milliseconds, often skipping them or displaying them for 50ms. It's probably not worth the hassle of different frame durstions. 50fps is the maximum for modern browsers, with some older versions of Internet Explorer being more like 10fps.
But it's certainly safe to say that these big, fancy animations are not what GIF was designed for, and you can tell easily by how large in size they tend to get. Fortunately, Chrome has recently started supporting animated PNGs (after Firefox has been doing so for years), which is certainly a step in the right direction, although mobile and Internet Explorer's lack of support will probably hold back the use of APNGs. A lot of sites tend to store animations as MP4s now anyway, or use CSS animation (neither of which you'll be able to do on here).
And although GIF doesn't really support partial transparency, I'm sure there was some sort of trick to get that working to some degree. It may have just been dithering.
One thing that I've managed to completely skip over in all of this is the fact that file size probably doesn't really matter to you. I assume you'll be using Imgur or something like that and how quickly a page loads on TBT for a first-time user doesn't make any difference for yourself. But it's still a good idea to keep images small when possible.
With PNGs, for example you can actually index them to ~256 colours to create a PNG8 image, which will result in an image about a third the size. If sticking to PNG24, removing the alpha channel when it isn't needed often helps, or simply using a JPEG when PNG offers no real benefits other than a lossless image. Oh, and don't get me started on JPEG compression - EXIF data, chroma subsampling and all.
I typed this long ramble on my phone. What a good use of time.
