I am going to assume you need one without a display, in that case go for
Wacom One by CTL-472/K0-CX Digital Drawing Graphics Pen Tablet (Red & Black) Small (6-inch x 3.5-inch) (~3.5K)
or
WACOM One by CTL-672/K0-CX Medium 8.5-inch x 5.3-inch Graphic Tablet (Red and Black) (~6K)
Both of them are excellent tablets and I have personally used both. I almost daily drive the CTL-472 as a mouse replacement and often use it for annotations and highlighting docs and rest. My mom who used to be a physics teacher has even conducted some lectures while using it. I have used it for illustrations as well. Even though it says small, the surface is quite large and should be more than enough for online lectures. Software compatibility and OS support are excellent (it might even work on a phone, if your phone is modern enough).
As for the medium one, we had gifted one to my aunt as she has to use the mouse a lot and often gets wrist injuries due to same. She uses it as a mouse replacement and she likes it a lot. I have not extensively used it, but in the few hours I spent with it, the larger area does help, but that also means you might have to move your hand a lot, and since I was very comfortable with the small form factor, it took me some time to get used to the larger area.
Both have battery less stylus and get the job done. There are other brands as well which might be a bit cheaper, but I often find them either using cells on the stylus, or geared mainly towards artists. The wacom one in that ways is flexible with general purpose tasks as well as artist oriented ones.