Have you seen Project MMO? It adds different skills to level up and adds level requirements to different stuff in the game. All of which is confiurable. Locks is a great mod to introduce the Lockpicking Skill!
The integration I imagine would be :
On successful lockpick gain x lockpicking experience depending on the lock that was picked.
On level up chance to break a lockpick when pushing the wrong pin is reduced

I am currently using Locks for 1.16.5 and it has been a lot of fun to play with! Amazing mod!
Thieves deserve to level up to! :)

Project MMO does have accessible API and the MCDoom mod has untilized it to award magic experience upon using the power orbs the MCDoom mod adds. Just for reference if you decide to embark on this journey :P
https://www.curseforge.com/minecraft/mc-mods/project-mmo
https://www.curseforge.com/minecraft/mc-mods/mcdoom