I have one additional piece of info to add to the puzzle.
I'm with Koodo (Telus discount brand) and they don't support wifi calling outside Canada (boo!). They also charge $14/day for roaming which is RIDICULOUS.
I found out I can disable the "Roam like Home" add-on in my plan settings. If you do that, receiving/making phone calls will cost $1.50/min (if I recall correctly) and there's no charge for incoming text messages.
So my new setup is:
1. Buy a local e-sim for destination data usage (if desired - I always desire, LOL)
2. Set phone to use the e-sim for data and the normal sim for calls/texts
3. If I receive any calls while abroad, tell the person I will call them right back, so the charge is only $1.50. I'm VERY unlikely to receive 10 calls a day so I will never exceed the $14.
4. Call them back using Whatsapp or VOIP on wifi or data.