Strip /lib from installed apk Most apks have a /lib dir inside with .so files that can be several megabytes. Some even come loaded with libs for different architectures (arm, mips, x86). Libs for relevant arch are copied in /data/app-lib/[package name] at install time, so they take double the space.

I tried to strip the apk from the /lib folder, rewrite, zipalign and put back to install location /data/app or /system/app or /system/priv-appto reclaim some space.

Tried with Chrome v78, it went from 45 mb apk to 15 mb...
Other apps too.
Everything seems to work.

Anyone thinks it's a bad idea? IMO the very Android system should perform this operation by default at install time...

edit 13 Nov

I wrote a script to automate the strip operation, just have to copy the apk to strip in a dir where this script resides, along with zip and zipalign binaries.

#!/system/bin/sh
for filename in `find . -name '*.apk'`
do
        ./zip -d $filename "lib/*"
        ./zipalign -fv 4 $filename $filename.new|tail
        mv $filename.new $filename
        chmod 644 $filename
done;


On my device I can swap original with stripped apks on the fly and they (usually) run fine  without rebooting, even system apps.
Based on my experience, modifying an APK file after the installation is not a big problem as long as you don't touch the DEX files. Especially the native libraries for other architectures than the one of your device can usually be stripped without problems as they are totally ignored after the installation. 

However there are apps that implement extra security checks (usually banking, finance, streaming apps with DRM or otherwise extra hardened apps) that performs some sort of self-test to check whether they have been modified or not. Modifying those apps will end up in a non-working app.