Drawing tablets are heavily used for creating educational content. For example you've probably seen the Khan Academy videos and those are created with a drawing tablet.
For this you want high reliability and durability and you DO NOT need to spend a lot of money buying a fancy tablet. And for those reasons I'll keep the recommendations short:
Pressure support - Will help you strokes look more natural. All drawing tablets have this pressure support.
Tilt - not needed for education use. More of an artist thing.
Tablet buttons (aka. ExpressKeys) - I think they can come in very useful for people. For some people these are critical. No harm in getting them, you can always disable them.
Size - Medium or Small. I always recommend medium. Even though some people are OK with small tablets, I do see a far number of people say the small size makes their hand feel cramped.
Pen tablets (no screen)
One by Wacom Medium (CTL-672)
Pressure: YES
Tilt: NO
Tablet Buttons: NO
Wireless: NO
Wacom Intuos Medium (CTL-6100 or CTL-6100WL)
Pressure: YES
Tilt: NO
Tablet buttons: YES
Wireless: Only the CTL-6100WL supports wireless
Pen displays (have a screen)
XP-Pen Artist 12 GEN2 (CD120FH)
Pressure: YES
Tilt: YES
Tablet buttons: YES
Wireless: NO
XP-Pen Artist 13 GEN2 (CD130FH)
Pressure: YES
Tilt: YES
Tablet buttons: YES
Wireless: NO
Wacom One GEN1 (DTC-133)
Pressure: YES
Tilt: YES
Tablet buttons: NO
Wireless: NO
Sal Khan uses a Wacom Intuos Pro Medium for his videos. That is an AMAZING tablet, but honestly overkill. You can get by with a much less expensive tablet.
Which specific model of Intuos Pro he is using?
It does NOT look to be the latest model of Intuos Pro Medium (PTH-660). You can tell this because in one of his videos he shows the tablet and I can see some things that clearly mark it as an older tablet.
The pen does not look like the Wacom Pro Pen 2 that comes with the PTH-660
The USB-cable connects with a thicker end and is not the L-shaped connector that comes PTH-660
The back of the tablet has the older Wacom branding.
Note that the Khan Academy has this document What software program/equipment is used to make Khan Academy videos? In that doc, they say he uses a Wacom Bamboo tablet. I suspect this probably was true at some point, but he clearly no longer uses it.
Teach with Khan - Sal's Tips for Creating Blackboard Videos for Remote Learning - this is the video where he shows that he uses Wacom Intuos Pro Medium tablet.
ClassPoint - Best Way to Use Wacom Tablet for Online Teaching with PowerPoint [One by Wacom] Dec 2, 2020
GRUMO - Teach with a Tablet (Full Tutorial + Demo) May 26, 2020