My experiences are as follows
I use Brave Browser. It blocks adds etc etc by default. On occasion I use Firefox.
On Brave Browser & Firefox, I have the duckduckgo privacy essentials app installed.
I also use Linux Mint 20.2 ...exclusively.
I access three different banks....almost daily.
i have used Linux mint since 2014 or thereabouts with no cause for either complaint or suspicion of trouble.
Personally I would not use Chrome. I would also not use Google.
For password storage I use BitWarden.
I find that it works. It is free. I have no complaint or fear of trouble.
Having said that I never store my banking passwords on a password manager, bitwarden included.
I think it is more than possible to overthink the situation.
As long as the password you use is not the name of your dog or your date of birth, then you have the best chances of staying secure.
If you regularly say to your wife....."I cannot understand the mindset of my grandchildren"......and if this is a phrase you say often....Then use that. Take the first or second or third etc letter from each word, make some of them capitals....add numbers (perhaps the ages of each grandchild......and you have a password that is incredibly secure.
Security is a mindset....your mindset.
The browser can help, but only if the password/passphrase is not easily figured out.
Where to store the passphrase etc ect ??....that is up to you and will be governed by the people in your house, etc etc. Remember your wife will need to know how to access it just in case you get hit by a truck or some other equally catastrophic occurrence.