I'll respond since this is a more general Samsung topic and I'm still on the S20 FE.
Email, Calendar and Contacts - Blackberry Hub+ Suite.
The Inbox (for emails) is supposed to be "old" and not support modern email security, but MS365 still works fine on it without any "less secure" setting needed. Both my personal and corporate emails work with it. It also integrates Teams notifications nicely.
I also like that the Inbox passes the color I give to each email account to the notification on the AOD and lock screen. Even Samsung's own e-mail app can't do that - showing the same ugly orange colored envelope icon regardless of which account it's from.
Same with the calendar. Reminders from different accounts show in the appropriate color. Samsung's calendar can't do that either.
Contacts are just easier to edit using the BlackBerry Contacts app. Although the stock Samsung contacts app still picks up those contacts. And it has to, so it'll work with the stock dialer.
SMS/MMS - Textra. I just like it better.
Backups - For the system, I use Samsung. I save some to Samsung's cloud, but they cut back on what can be saved. The rest, I save directly to my SD card (since this phone still has one) and to my PC.
Photo backups - OneDrive, and direct copy to my PC.
Keyboard - BlackBerry Keyboard. I like the swipe up from the key function for word selections (better than picking from a list above the keyboard). Just a habit from the days using a BlackBerry Z10 which originated that feature.
Voice Assistant - nothing.
Browser - Firefox.