As for frontend - you could build reusable components and make possible to use them/build upon them. Microsoft made FluentUI to make consistent and usable compo

As for frontend - you could build reusable components and make possible to use them/build upon them. Microsoft made FluentUI to make consistent and usable components across product line. However each product customizes styling slightly and builds their own components that are not opened up... which is pity. If you ever plan having different things, better keep them in mind at the beginning - bolting them in afterwards may be cumbersome.