That's solid advice, but I'll add: the item-stealing route gets boring fast imo, and you'll actually want to practice locks eventually anyway since you're going full thief. Might as well bite the bullet early.
What I do on thief builds is just accept the lockpick tax for the first 10-15 levels. Buy a stack of 50 from the Thieves Guild fence (or any general goods vendor), hit some low-level dungeons, and treat failed picks as part of the grind. You'll burn through them, yeah, but you're also building muscle memory for when it matters. Plus you'll find enough loose picks in those same dungeons to offset some of the cost.
The perk that cuts lockpick breaking (pretty sure it's called Wax Key or something like that - the one that halves damage) genuinely changes the game once you get it. After that you can basically lock-pick everything without sweating it. So it's not forever, just a rough patch.
If you're really strapped for gold early, grab the Standing Stone that boosts your Thief skills (the Shadow stone, I think?) for that first stretch. Speeds up the grind enough that you hit the perk sooner and spend less overall.