Very detailed document, but it seems to me that there is not enough description about:

a) additional playstyle architype - a knight, when you take a small race and compensate their low mobility by a beast steed. Here you can add that you can by armor to your beasts, but four times more expensive (Barding rules from PHB) and that feat "Mounted Combatant" can increase the survivability of your beast to unprecedented heights

b) some shenanigans with "fog cloud" and beast with blindsight. Plus we get additional fighting style that improve this kind of a playstyle in Tasha's Calodrone

It would be interesting to know your opinion on this. Kind regard