You can use tabbed[1] or a multiplexer like tmux, or you can use a different terminal emulator like kitty[2].
For example, instead of launching `alacritty`, you would launch `tabbed -c alacritty --embed`.
Kitty it is.
I'll give Kitty a shot. I've been using konsole recently and it works for the most part, except when sending files through picocom. ctrl-a+s pops up a message about terminal flow control even though the keystroke is intercepted by picocom and not used for flow control.
When you subsequently want to move a group of things around, you can focus the parent container and move it around as though it were a window. (Out of the box, Super+a is `focus parent`, though curiously there’s no `focus child` binding in the default config, so to return to a child you pretty much have to focus a sibling or another container, or use the mouse.)