KDE Connect

LocalSend? https://localsend.org/

KDE Connect can do clipboard contents, notifications, SMS from your PC, and file transfer, but I like Syncthing's approach of folder synchronization better than sending files individually. I use both.

Localsend: https://f-droid.org/packages/org.localsend.localsend_app

I use local send. It's fantastic

Kde connect

Use primitive Ftp or solid explorer on the phone to mount your phone's disk right on your pc. On the PC side Dolphin (Linux) or freecommander (windows) are great file explorers for this. I also use KDE connect, but the ftp mount is way more powerful.

Onionshare should work. You temporarily (or longer if desired) turn a folder/s into an onion site, which you can use to share between computers, not limited to just your own but also to others you give the key to.

For files I use localsend to transfer directly between devices on the same network.

Syncthing

Since Syncthing and LocalSend are already mentioned.

Transfer is another alternative.

i use copyparty, connecting thru browser. but i also still use telegram saved messages like you because having a timeline helps my workflow. i wonder if there's an alternative to that.

Since Syncthing and LocalSend were already mentioned - let's throw in Warpinator:

• built by the Linux Mint team
• has had an (inofficial) Android client for a while now
• works well (although Syncthing is a lot more powerful and requires fewer clicks once it's set up)

Blip: https://blip.net/

CX Explorer using FTP

Kongpiler2 says kdeconnect, if you're using KDE it's extremely efficient. An extension is also developed for Gnome to employ kdeconnect but my experience with that was marred by connectivity issues. Something to bear in mind.

I use good 'ol FTP for irregular transfers. Mobile side, I use Ghost Commander, which is a file manager with FTP support. On my computers, I usually use vsftpd, but there are simpler programs like uftpd. You can also access remotely and/or securely if you use an encrypted overlay network like yggdrasil.

There are plenty of good suggestions already, but one thing I do very often to get text from my computer to my phone is just displaying the text as a QR code and scanning that. You can make it work the other way around if you have a webcam, but that's a bit more work.