My kid's school has everything online also (office 365 online etc) so I just bought my daughter a chromebook (6th grade) and it works fine. I picked one up for $80 on Amazon but it seems that prices have jumped recently - maybe because everyone if buying them for their kids!
Yep, both my kids use Chromebooks. We bought one for my son, then we had to buy him a new one directly from the school for 6th grade, so his little sister got his old one (and she was actually very excited and not mad to get a hand-me-down).
Oh and a bit of advice - they'll need a google account to be set up but don't put their real date of birth in if they're very young. I did that for my daughter and her teacher was asking her to watch YouTube videos and it won't let her because she's under 13 so only has access to YouTube kids. If I recall, it also didn't let her add Zoom to her browser. So I had to set up anther account with a fake age.