If i had a mounted archer character i would probably make the mount an expert sidekick.
Faithful steed homebrew feat.
+1 ASI(or without it as Origin feat)
gain large size steed as a companion.
you can summon it as a ritual spell(10min)
STR 14, DEX 14, CON 14, INT 6, WIS 12, CHA 8
AC: 12+prof bonus
HP: 5+5×your level
Speed: one out of 4 options
1. 60ft
2. 40ft and 40ft Climb
3. 30ft and 30ft Swim+waterbeathing shared with rider
4. 20ft and 60ft Fly, requires level 9
You can command your mount as Bonus action or one attack from Attack action.
Otherwise mount can take movement, Dash, Disengage, Dodge actions.
Action: attack, bite 1d6+STR+prof bonus damage, attack roll d20+2×prof bonus
Bonus actions: Dash, Disengage, Help
Proficiency; proficient in all saves.
Skills: Athletics, Acrobatics, Stealth, Perception(expertise), Survival