If you're using your company's network, then they have every right to monitor all of the activity on it.
This is tantamount to steaming open and resealing the envelopes of all physical mail. Have some god damn ethics, I'd sooner quit than snoop traffic in this manner.I would never trust a company device, or company network, with anything I consider sensitive. Use your own device and keep it on cellular.
Also though I don't like it, employers in the US do have the right to open mail addressed to you personally if delivered to the office.
What you do while on work should not be personal and thus cannot be snooped upon.
If you need to send a personal paper letter, you would go to the post office, not send it using the company's stamps, right?
(Note: I would also never trust a company device or company network, and I keep my personal devices completely separate from the company network for this reason. But I consider this a workaround for a deplorable situation, rather than just the way things are.)
I would argue against such an approach if there are alternatives but if the organization's leaders were set on it I would engage with the process and make sure that it did not evolve into more unethical practices such as logging all traffic contents or the above banking example.