Keep in mind that Proton has recently made some dubious political statements and decisions, and I wouldn't endorse a product by such a company. The product is still good, but the trustworthiness of the parent company has recently been debatable.
On a more serious note, NOTHING with more than a little complexity should be written in shell scripts imo. For that, Python is the best, primarily due to how fast it is to prototype stuff in it.
In my opinion, most people won't get confused by the 'old' interface being at a different subdomain, especially as Reddit did it themselves (apparently they had new.reddit.com which hosted an older redesign than reddit.com, like wtf!?? But somehow people understood that distinction, so this should be fine) Then again, I could be too much of a nerd and overestimating people :P (insert relevent xkcd here)
That's why I use nushell. Very convenient for writing scripts that you can understand. Obviously, it cannot beat Python in terms of prototyping, but at least I don't have to relearn it everytime.
Aside from the fact that this is not the correct community for such a question, I'd recommend checking out Privacy Guides to get started on your privacy journey. Check out their recommendation for e-mail providers.
Keep in mind that Proton has recently made some dubious political statements and decisions, and I wouldn't endorse a product by such a company. The product is still good, but the trustworthiness of the parent company has recently been debatable.