To your primary question, yes I've used a knife as a can opener. Many times.
Every occasion where this has happened was while I was in the military, using my military issued Leuku knife from Strømeng. That knife was used for everything, so edge damage wasn't a big concern.
As a civillian, this is a non issue.
At home I rarely use canned food, if I do they usually have pull tabs, if they don't I have a dedicated can opener in my kitchen drawer.
For every other occasion, the need to open a can of food does never arise totally unexpected, so a can opener is not part of my edc.
If I go backpacking or camping I will bring a SAK with a can opener. In Norway we have hundreds of open cabins in the mountains, all of these have stocks of canned food that you can use if you want to save on weight, if you run out of food or find yourself in an emergency. Most of these cabins will be equipped with a proper can opener, but sometimes they are broken or can't be found, so you never know.
Depending on season or type of trip I'll carry a alox Bantam, Cadet, Sportsman or Compact.
I also have a can opener in my car, in case I need to open a can when we're car camping.
I used a P38 in field exercises at Fort Knox
in the Armor Officer Basic Course in 1969.
Nothing like sitting in a 50-ton tank (an M60)
freezing in the snow eating cold C-rations.
But it could have been a lot worse.
I would go on to be stationed in Germany
instead of Vietnam.
1990: Endura SE, Delica PE, Mariner, Police. 2014: ClipiTool Bottle Opener. 2015: Kitchen Knife PE, Tenacious CE, Stretch PE, Moran Drop Point, Kiwi, 2 Byrd Cara Caras, Schempp Bowie, Native 5 Forum Knife, Police SE, Tenacious SE, 4" Paring Knife, 2" Paring Knife, Terzuola Starmate. 2016: The Spyderco Story, Terzuola The Tactical Folding Knife, USN Ladybug H-1 Hawkbill SE, Black BaliYo, Yellow H-1 Salt Dragonfly 2 SE, Hennicke Ulize, Pink Native 5 PE, Renegade C23PS and C23P, Gayle Bradley 2, Terzuola Double Bevel, Gayle Bradley Air, Cricket Blue Nishjin, Centofante Memory, K2, 2 Large Lum Pink, Carey Rubicon. 2017: Dialex Battlestation, Orange Southard Positron, Gray Baliyo, Native 5 CE, Tenacious CE. 2018: Schempp EuroEdge, Eric Glesser ClipiTool Standard. 2019 Calendar Contest Reinhold Rhino CF PLN. 2022: Byrd Robin 2 Wharncliffe, Byrd Cara Cara 2 Rescue Orange, Yojimbo 2 CruWear. 2025: Stok Bowie, Natural G10 Dodo. Motorcycle Adventures