You bring up several good questions here. Also, I'd love to check out your Go imageboard software. Can't lie that I've been doing a similar project, hah.
>Do we need yet another imageboard software? I mean do we have enough people looking to new imageboard software?
This is a tough question. I'd say the first part is largely philosophical. There are a lot of options, and there is a lot of variety among them. But imageboards are a fun software to work with and there's always something new that one can attempt to apply to the imageboard dynamic. For the second part, I really don't think the audience is there anymore. I feel imageboards and *chans in general are becoming a niche thing.
>How much is too much? Is 50mb of deps too much? Do we need a new stack? For example I plan to do my software run on containers as you'll only need a simple script to update it as Go binaries are 7mb/15mb.
I think it's all based on what the developer is trying to achieve. Are they looking to emulate a full suite of imageboards like 4chan? Maybe they just want one imageboard? Maybe they want it to be real-time with multi-file video and audio uploads?
Dependencies and programming language stacks I feel are really up to the choice of the developer as well. You don't NEED dependencies in most cases, but they can provide you with tooling and features that would otherwise take a lot of time to create yourself, as well as maintain.
>Do we need new features? User accounts so you can keep track of replies and watch threads or even a new "UI/UX"?
This is a matter of what audience you're trying to cater to. If you make a 4chan clone, you can expect a majority of your audience are the same people who would use 4chan. User accounts are a highly controversial topic in imageboard software, see https://wakaba.c3.cx/shii/
for more on that. A new UI/UX for imageboards is always something I've been interested in, since imageboards generally use a layout that dates to the late 1990s.
>Do we follow bigger software standards as response layout (vichan's .json endpoint)?
Creating a standard for imageboards is always something I've been interested in. I do feel that imaPost too long. Click here to view the full text.