A lot of the GNUisms described in https://jmmv.dev/2021/08/useless-use-of-gnu.html are very useful in interactive use. Search the current directory without an explcit . - useful. Append an option to a command you just typed - heck yeah, always annoyed when commands don't support that.

For scripts though, sticking to POSIX sh often makes sense, yeah. You should at least be aware if you use of Bash-isms.