I could never get started with kermit - it's a huge ecosystem into itself, with its own scripting languages, file transfer protocols, etc...

Instead of trying to buy into that, I found out that individual tools are much nicer with. Minicom for fancy conversations. Custom scripts/picocom/tio for basic ones. Perl (later python) to script. zmodem to transfer files (or xmodem if the memory size is extremely limited).

But the biggest replacement is SSH of course. For the last 20 years, most of the devices which have serial ports also have Ethernet access. Use serial port to bootstrap, and then switch to SSH. "dropbear" is tiny and has very few dependencies, and yet gives a vastly superior experience compared to old serial terminal: multiple connections, file transfer, scriptability, etc...