Despite everything, Telegram is actually great. It’s only bloated if you’re using the features on the device, the client is opensource and there are native apps for any platform, it’s very lightweight compared to other messengers and even to some dedicated filesharing solutions, it sends stuff p2p on the same network so you don’t need to care about the traffic, but also it allows for on-demand downloads so if you want the stuff will be available outside of your network.
Alternatively, kdeconnect, but I find myself using Telegram instead 9 times out of 10, even though I have both installed.
Doing arithmetics quickly is a skill that is slowly dying out of the general population. When we all used cache we had this with us all the time, but now we just don’t use it that often, generally, on average