Nice summary-type article on using an RPi as a "productivity powerhouse" (https://opensource.com/article/21/1/raspberry-pi-productivity). It covers mail and calendar apps that run well on the Pi. Hint: no mention of Thunderbird here. Interestingly enough, the author found that Evolution runs well on a Pi, despite it being much heavier than the other mail apps he refers to.
I have to admit I'm impressed with the power on the Pi 400 I purchased. It is easily as quick as a Chromebook, but offers far more capability.
I don't get much time to use it... my daughter found out it had Minecraft and has essentially claimed it as hers :)
Sounds like you may have to become a 2 computer, RPi 400 family. :-)
Just what I need, more computers LOL ;D