A fair number of my contacts from countries where this is true also have Signal. If you don’t, I suggest installing it and seeing how many people are there.
If it’s hard to remember who uses what, start conversations from the contacts app instead of one of the messaging apps; in most cases it will tell you.
I did not experience this, and I’ve been using Signal daily for years. Prior to 2020 or so, I experienced more unreliability and hesitated to recommend it to the average person.
I’m familiar with the problem though; in most of the EU and probably other places WhatsApp usage is so high that it’s a major inconvenience to avoid it entirely.