You got three options.
First option : Use ChatGPT/Deepseek and ask help. I did it to look, and it seems feasible, and you can specify your wants and ask for help over what to choose over the frontend/backend/database.
Second option : You take a ready-made opensource imageboard software like lynxchan for example. You can always find something that you like and still supported. And customize it when you are familiar with the code.
Third option : Pull up your straps and do it yourself. Ask for help if you don't have any ideas, like the programming thread on KF, and ChatGPT/Deepseek.
The downside is that if you use ChatGPT/Deepseek, you can't be 100% what it is feeding you is correct or secure. Yes it can help with the basics, but you will have to get your hands dirty to do better if you don't want to end up with the shitcode of 4chan.
The best thing to do is try and learn from your mistakes. And perhaps integrate A.I bullshit (autodelete bad pics/vids and links to trooncord or shit like that) to not get bombarded with bots/cp.
Mind you, I don't have any ideas either, what I'm saying is a result of the last few days mucking around Deepseek asking for answers lmao.