So to lay out the more specific model as presented in the Circle of Wildfire feature "Summon Wildfire", but adapting it for Ranger, here's the rough outline:
1) Form of the power: The Druid feature is a summon. Ranger's can be a summon too, or we can go with an existing animal. Which creates some mild issues but nothing we can't work through.
2) Activation: You expend an action and use a limited resource to activate it. The druid is spending a Wild Shape use. The Ranger could spend a spell slot.
3) Initial Move: The Wildfire appears in 30 feet. If the Beast is an existing companion, it could just move it's move on activation.
4) Initial Action: The Wildfire immediately "attacks" every creature in 10 feet of where it's summoned/moves to other than the you, requiring a save or take an average of 11 damage. For a beast, I think we could instead issue a Command for that round, as detailed in #6 below.
5) Initiative: The Wildfire shares your initiative count but takes its turn immediately after yours, and the Beast can do the same.
6) Actions In Combat: After activation, the Wildfire only takes the Dodge action unless you take a bonus action on your turn to Command it to do any of the following instead: 1) take one of the actions in its stat block, or 2) Dash, or 3) Disengage, or 4) Help, or 5) Hide.
7) Ranger Action Variant: Now because the Bonus action to issue a command can interfere with one of the Ranger's iconic fighting forms of dual weapon fighting, I think it might be fair to say the Beast follows it's last command on following rounds until issued a new Command? This one will take some more thought.
8) Advancement of Stats by Level: The stats for the Wildfire have some built-in advancements with level. HP = Con Mod+your Wis+ (Your level * 5). That's a likely starting HP = 2+3+5=10 at level 1, 15 at level 2, 20 at level 3, etc. until your Wis goes up. This could be adapted for a Beast. The Wildfire sees the following numbers increase by 1 when your proficiency bonus increases by 1: skill and saving throw bonuses, bonuses to hit and damage. This can be adapted to the Beast. I'd say Beast DCs for any abilities it use also would increase.
9) Pet Survivability: The stats for the Wildfire include a lot of immunities a Beast normally wouldn't get, like fire, charmed, frightened,grappled, prone, restrained. It can also fly, and has 60' darkvision. These increase it's survivability and utility. Not sure how to adapt these concepts to the Beast but I think it could be done.
10) Types of Specific Pet Actions: The Wildfire has two actions it can specifically take on in it's stats, in addition to the general actions it can do as mentioned above. They are: A Ranged Weapon Attack: +4 to hit, range 30 ft., one target you can see. Hit: 1d6 + 2 damage; and a Teleportation power that Recharges after a Short or Long Rest that teleports each willing creature of your choice within 5 feet of it up to 30 feet, and then each creature within 10 feet of the space that the spirit left must succeed on a save or take an average of 5.5 damage. Obviously there would be pretty wide variance for Beasts in what actions it can take, and there would likely be different Beast options each with their own different abilities and attacks and such.