Reverse-Engineering an Apk

Hi, I'm relatively new to App Development and just generally the Mobile side of things, but recently android development has caught my attention. Due to the frequent use of my school's mobile webapp - which is under Ionic framework and Apache Cordova from what I managed to find - I figured I'd like to tweak some parts of it to suit my needs a little better: i.e. Offline viewing of my timetable, auto-attendance, dark mode.

Since I'm basically a rookie cookie here, I'd really like some help knowing where to start or even how to start on this journey. What I've done so far is decompiled the apk with 'apktool' and all the .smali files spew alot of things.

TL;DR

Need guidance to reverse-engineer a web app

some solo digging uncovered that it has cordova and ionic in it

Super Clueless rn..