I’m sure you are aware of Esperanto.

https://en.wikipedia.org/wiki/Esperanto

I preferred Interlingua...

But these days, Slovio would help me more.

I've tried Slovio on Slavs of about 10 nationalities. None had ever heard of it. All of then, no exceptions, could just understand it perfectly well, to their great surprise.

https://www.interlingua.com/interlingua-en/

https://www.slovio.com/