Kamrul Hasan, Don't choose dying technologies with small communities. How many startups do you think use Spring and Django? Use Google Trends to compare technologies. Study the StackOverflow developer survey and job websites to see what technologies are wanted. Few teams can afford to train you to get up to their level so be a life-long learner. Embrace the dawn of a new industry and become an expert.
You can get done what you want with just about any modern framework and language.
Django is fast and easy to learn but as your website grows you will need more and more community apps whose release cycles do not keep up with Django. Unless you are willing to work on the community apps, Django may not be for you.
Compare the active community sizes of Django apps to Ruby on Rails apps and you'll see very active communities with Ruby on Rails and small Django communities. Don't switch to Ruby on Rails though--it is a small, dying community of enthusiasts.
ASP.NET Core is a great backend framework, the community is large and you can always find answers; however, according to the StackOverflow developer survey, it is not desirable for the majority of programmers. I still use it though because my background evolved from C to C++ and then to C#. I also like the Microsoft world.
I've programmed a lot using Angular and some React but am switching to Vue.js which is much easier to learn and faster to code in. Be sure to use TypeScript with Vue.js. Just watch the video on the Vue home page to see how fast he can code using Vue.
But do you really want to code a website from scratch? If not, try WordPress Elementor. It may save you tons of time.
For mobile, use Google Flutter. In my 35 years of professional programming I've never seen anything more elegant, easy to learn, well documented and beautiful than Flutter. From one a single base you can target both Android and IOS and soon Web. You can also develop in Android Studio which means your screen real estate requirements are small so you don't need two monitors.
Thanks a lot, in fact we (our tiny team) had considered WordPress, but it didn't meet our needs. We should develop some plugins and other problems. In addition wordpress may can help us at first, but if we chose that, we would have to change our platform to something else. So we decided to build our website with a better technology and do not doing something twice!