If you do need (or simply want) to use a front-end framework, I would pick Vue.js as it's designed to be 'gradual' and so has a smoother learning curve. I suggest using single file compoonents (.vue extension) with properties and events and go without a central shared state.
Historically, React has been more popular and has a bigger job market. e.g. I use React at work and Vue for personal projects. I can't comment much on Angular other than the 1.x/2.x+ split isn't great for googling answers and many Anguar apps I've used are slow.
"Focus on product" as @maxxxxx puts it is the best advice. Work backwards from a goal. E.g. I want to release a product with x,y minimal features by z date on Product Hunt. Try to get others' hand on your app to get feedback and drive development based on usage/needs.
Also, don't be afraid of embracing multi page app versus going for a single page app (they're largely overrated).
For front end CSS design framework, I'd recommend something like Bulma. Very easy, modern and CSS-only. You can learn it all in less than an hour.
For the frontend, it depends on your goals. If you need a quick prototype, just use the Django templating engine and ship something quick. If you want to learn, choose a popular frontend framework and stick to it. They are all pretty good. Check their API / ecosystems and pick the one you like :)