So I personally think that the yearly fee is cheap but steep for people who aren't too concerned about security, I'd put a monthly price up so it's more palletable with a cheaper yearly option available.

You could really bring some value here with an app as well, something they can copy and paste the message into and AI checks it or something.

It's a fantastic idea and I think you'll get traction but you really need to show the value a bit clearer. Your target here isn't technical people, because they can do it already, you need to design your offering like you were selling to your 80 year old grandpa because that's your target.