The main complaint I have at the moment for the line tool hotkey is when holding down the hotkey for the line tool (which is currently "v" ) it'd activate the line tool, but when you let go, instead of it going back to the brush tool, it would go to the "select" tool. I feel that this greatly causes a break in workflow when trying to work on an art piece that would require going back and forth between brush tool and line tool multiple times.
Some may suggest to just use a hotkey to activate the brush tool afterwards, but that may not always be an option for individuals like myself who's currently working from a standalone tablet (Wacom Mobile Studio Pro 13) that only has so many buttons to assign hotkeys to.

In general, the change suggested in which the hotkey for the line tool would go back to the "brush" tool instead of the "select" tool would make for a more seamless workflow without having to go back and forth with so many different hotkeys and clicks.

It'd also be great for the line tool to also have an option or settings of some sort to have pressure sensitivity and to also have an option to draw in similar parameter properties of the selected brush used so it's not just always a completely solid line in the size of whatever the current brush size is set to. The current function of it outputting completely solid lines at max set brush size regardless of the selected brush and its properties, is really deterring me from using it more often unless for something specific like solid line art.

Um... If I press V with the freehand tool selected, and then let go of the V key, I go back to the freehand brush tool.

Well that's strange, because mine goes to the select tool instead. Would this happen to be an issue or a bug because it being a standalone tablet with a button being assigned the "v" key instead of it being an actual keyboard "v" input?

I'm afraid it's impossible to tell without actual access to your system I'm pretty sure though that it's a configuration issue, and a not a bug in Krita, because, well, the subsystem isn't in Krita at all, it's part of the development framework.