In App Inventor there is something called obfucated text. It doesn’t really improve security also but for a standard hacker it could be enough to be stopped.
This is the code in java.
Blockly.Yail[‘obfuscated_text’] = function() {
// Deobfuscate the TEXT input argument
var setupObfuscation = function(input, confounder) {
// The algorithm below is also implemented in scheme in runtime.scm
// If you change it here, you have to change it there!
// Note: This algorithm is like xor, if applied to its output
// it regenerates it input.
var acc = [];
// First make sure the confounder is long enough…
while (confounder.length < input.length) {
confounder += confounder;
}
for (var i = 0; i < input.length; i++) {
var c = (input.charCodeAt(i) ^ confounder.charCodeAt(i)) & 0xFF;
var b = (c ^ input.length - i) & 0xFF;
var b2 = ((c >> 8) ^ i) & 0xFF;
acc.push(String.fromCharCode((b2 << 8 | b) & 0xFF));
}
return acc.join(’’);
}

Like it says it acts like xor.
When i make an app where i use for instance a baserow url, I put the url in the obfuscated textbox instead of putting it in a normal textbox.
So if you use a xor function to make the url less readable you wouldn’t need an encryption key.