Yes, you can have multiple duck addresses at the same time. There’s a personal and private duck address.
Composing email: https://duckduckgo.com/duckduckgo-help-pages/email-protection/duck-addresses/how-do-i-compose-a-new-email
About duck addresses: https://duckduckgo.com/duckduckgo-help-pages/email-protection/duck-addresses/can-i-create-multiple-custom-duck-addresses
I also used SimpleLogin and loved it until I subscribed to the Proton products. Like you, I haven’t needed to use SimpleLogin because of Proton Pass. Haven’t used iCloud since 2021 and have no regrets.
Ahh, apologies then. I thought OP wanted to de-google. I use DuckDuckGo because of their duck player; it opens YouTube on a separate window without all the extra stuff you don’t want (just the video you wanted to see). I guess OP can use PeerTube? I’m quite happy with my Proton Unlimited but it’s not for everyone. And yeah, I’m a browser hopper.