If you want to practice investing, give the 1984 hit video game Drug Wars a shot.
greybeard
So I and some others here have probably sounded a bit antagonistic to you, but good on you for asking and trying to understand. Public Key Cryptography feels like magic to me too, it's just magic that I've accepted exists without understanding the base math of it all. Without it, however, most of the security of the Internet doesn't work.
Even most symmetrical encryption (Like AES, which is how you are picturing encryption working) layers on asymmetrical encryption as a negotiation layer to share a key that both parties have but that nobody eves dropping can read. Then once the key is exchanged, they use that because symmetrical encryption is way easier for computers. But for short messages like Signal sends, it wouldn't surprise me if they stay asymmetrical for the entire communication.
Signal does hold the public keys for every user. But having the public key doesn't let you decrypt anything. You need the private key to decrypt data encrypted with the public key. So in a chat example, if you and I exchange public keys, I can encrypt the message using your public key, but only you can decrypt it, using your private key.
Signal does run the key exchange, which means they could hand a user the wrong public key, a public key which they have the private key for, instead of the other person's. That is a threat model for this type of communications, however, signal users can see the key thumbprints of their fellow chat participants and verify them manually. And once a chat has begun, any changes to that key alerts all parties in the chat so they know a change has happened. The new key wont have access to any previous or pending messages, only new ones after the change took place.
The server can't decrypt it if it doesn't have the keys to do so. It can be proven that private keys never leave the local device. It can also be proven that the proper public keys are being provided, and that the local device alerts on public key changes with a partner are announced.
Of course, nobody as part of the linked article did any of that verification, but still, a server doesn't need to be trusted to be functional.
I replaced pocketcast with Antennapod a year or so ago. It took some time to adjust, but I'm quite satisified with it now. I feel like I'm slowly converting over at an F-Droid stack on my phone. About all I have left from the Play store are streaming apps and banking apps. I should look into replacing the banking apps with PWAs.
Disasters do happen. Hurricanes are a big problem that often take out everything you mentioned except for starlink. And starlink has several problems, being owned by a Nazi is certainly one of them.