Linux is a mixed bag. Linux CAN be more secure than Windows 10 and many banks us Linux for their servers. Alot depends on the specific implementation. Some vendors do not support Linux especially if there is a client side required component. However, browser based implementations will generally support a modern Linux version with a modern browser.
I personally use Linux Mint as my home PC. Note that there is an security module that can improve the security of Linux in general. However, it does require some reading and understanding of security controls.
https://en.wikipedia.org/wiki/Security-Enhanced_Linux
I have never tried linux to log into my bank. It is probably the banks prerogative to support linux or not.
We use a win10 pc for our banking.
I use Linux mostly facing the Internet.
The W10 not so much.