Interlingua
en.wikipedia.orgIt's better than Esperanto in my view but has very little in the way of users and little cultural output. (At least Esperanto has tried in that department.)
I’ve never heard of it, but could easily read their homepage. I’m a Portuguese speaker, which is, IIRC, the fifth most spoken language. If it’s readily understandable by others who speak other neo-Latin languages, then it covers a whole lot of people in Europe and almost the whole American continent.
I've heard of it before. Not to be confused with the similarly named Interlingue, Lingua Franca Nova etc.
I find it pretty easy to understand. I imagine the challenge for you and other Romance speakers might be in using it actively since you would unconsciously put Portuguese/French/Castillian/Italian/Catalan/Romanian etc grammar and vocabulary.
This is my problem with Spanish. It doesn’t matter how much I try, I end up speaking Portuñol.
https://neolatino.eu/ is really cool, a direct Romance IAL
Looks like a natural language. If I saw that I would presume it was an Italian dialect/vernacular from the north.