The DnDOne version "sort of" does this, but I'm not sure if it's any easier than any other version of Druids. Their lvl5 class ability let's them trade in spell slots for more wildshape charges, and even by lvl5, that's a lot (even if you just trade away half your casting potential). Cognitive problems would probably go up to most players/ DMs with the weird spell slot/ wildshape pool this can give you.

For a suggestion, I'd just reskin a Totem Barb into a Druid, and give them one spell slot every two levels. So 1lvl1 slot at character lvl1, 1lvl2 at lvl3, 1lvl3 at lvl5, etc. And a couple known at each slot lvl. Barbs are notoriously underpowered anyway, so a bit of magic isn't going to hurt the balance much. Give them Guidance to start, so they feel mystical and wise and helpy. You choose the spells for your player, but you can change them if they want to do other awesome stuff.

So you get "beast form"/ Rage, and a bit of magic. Even let them change their totem each day if you'd like, so they're good at doing different stuff. Maybe start with Goodberry/ Jump, then Enhance Ability/ Summon Beast, then Plant Growth/ Tidal wave.

The player can choose if they're doing druidy things, or magic combatty things, or beast raging. Might work.

(Or do what you were going to do, that would work too)