Symbiflow is really a set of command line tools that take HDL language (text files, e.g. Verilog) to "compile" them (synthesize, place & route, generate fasm and finally generate an FPGA bitstream from it), very much (spiritually) like gcc or llvm (that take e.g. C code and spit out a binary). Therefore IDE is the programmers choice.

VS Code is definitely one option. I personally prefer old-school console tools like vim + console.

Unfortunately I never went much into vi(m) unless absolutely necessary. I don't mind the console aspect of the synthesis, placement and routing process.

As projects get larger and you have more and more modules, I find that text only editors lack the ability to click and jump between them. Not a deal breaker, but a nice to have.

what I am trying to say is that the toolchain is not limiting your ability to choose anything you want. So anything that works for you is suitable. There is no technical limitation in Symbiflow (to my knowledge) that prevents you from using any code editor you want.