https://github.com/kennell/imageboards might help you a bit, i should somewhere have a more detailed list about image board software on my bookmarks … somewhere.
Towards your second part:
It depends on different factors.
What do you want to do with the board? Just a small plattform for a few friends -> spare the hassle and use a premade one. You want to build something more persistent or bigger? -> Building a board yourself could become a fun adventure.
How much experience do you have in webdev and programming in general? There is that "I have learned some Scratch and now i want to build an MMORPG / OS all myself" Stereotype for a reason. I don't want to disencourage you, just say that building a board is not a trivial and it could be wiser to start with smaller steps.
If you understand the complexity of what you want to build, do you have the ressources (e.g. time and motivation) to do that?
There are things to consider, but i hope these questions will help you a bit. In the case that you want to build a image board yourself, >>>tech might actually be able to help you, if you are able to filter out the usual shitposting. Also, if you coincidentally want to write it in Haskell i might be interested in helping you build some cool stuff.