Grid polyfill for IE

[snakemastr]

I have a question regarding Grid and IE.
I had used grid with gap and grid-cols-* classes but client wants to support IE11. When enabling Postcss autoprefixer I'm receiving all kinds of warnings like described in #1586.

Would it be possible to polyfill grid utilities with flex classes for IE 11 only? So we can keep using grid for the advanced browsers but keep the layout similar on IE11. If so, how would such an approach work?