im not a hud editing expert or anything, so i dont really know. most editing i did also places the speedometer in a separate file and has hudplayerhealth load it using #base, but i assumed it didnt matter. all i know is i can get it working myself in the huds i upkeep. the other speedometer might be better anyways, since it takes up less space. i've edited the original post to include the step of creating a second file.

i dont believe so. the current vmt that the speedometer uses is made with a "material proxy" and looks like this:

"UnlitGeneric"
{
	"$basetexture" "vgui/replay/thumbnails/numbers"
	"$translucent" 1
	"$vertexcolor" 1
	"$no_fullbright" 1
	"$ignorez" 1
	"$speed" 0
	Proxies {
		PlayerSpeed {
			scale 1
			resultVar $speed
		}
		Clamp {
			min 0
			max 9999
			srcVar1 $speed
			resultVar $frame
		}
	}
}

right now it just takes the vmt proxy "PlayerSpeed" and if you have a look in this list of material proxies there doesnt appear to be an alternative that gets only horizontal speed.

recently, i made a speedometer for tf2. saw the idea from aimisadick about 7 months ago. i've generated about 3,500 images and combined them into one vtf so that it can display speeds of 0 to 3500 (most servers cap speed to 3500) and it takes up around 14 megabytes. it looks like

https://youtu.be/5LCuYVeoMjY

to add to your own hud, simply download this zip and copy it's "materials" folder to your own hud. then, create a new file inside [your hud here]/resource/ui called "speedometer.res" and inside paste the following:

"Resource/UI/HudPlayerClass.res"
{
	"speedometer"
	{
		"visible"			"1"
		"enabled"			"1"
		"controlName"		"ImagePanel"
		"fieldName"			"speedometer"
		"zpos"				"-100"
		"xpos"				"cs-0.5"
		"ypos"				"c85"
		"wide"				"50"
		"tall"				"12"
		"image"				"replay/thumbnails/numbers"
		"scaleImage"		"1"
	}
}

you can adjust the "wide" and "tall" values to get a better size, and you can add more to the "ypos" value to get it further down.

then, at the top of [your hud here]/resource/ui/hudplayerclass.res, paste the following text:

#base	"speedometer.res"

you can edit the transparency and color of the speedometer by going into "vgui/replay/thumbnails/speedometer.vmt" and adding things like

"$alpha" "0.5"

for the transparency (between 0 and 1) or

"$color" "{ 255 50 200 }"

for color (rgb 0-255).

enjoy!

most of my feedback is probably stupid, irrelevant, incorrect, and useless but here it is:

things i'd change:

i'd make the health and ammo closer to the crosshair, perhaps in a minmode toggle. i do know however that some people find numbers closer to the crosshair distracting, so you probably shouldn't.
i'd also make the font on everything that isn't the health and ammo completely different, otherwise perhaps choosing a font that is more "readable" (not that handel gothic isn't readable, rather other fonts are MORE readable than it). this could probably also be solved by making a seperate version of the font for the health and ammo specifically, and making that version "bold-er" if that makes any sense (it probably doesn't).
i'd also say to make things like displaying your name, profile picture, and friends list in the main menu optional, i hate seeing them, although this is honestly a nitpick and i'm probably just a loser.
on the topic of the main menu, making pretty much all the text larger there would be really nice.
i'd also use the colors for buffed and low health on spectator for playing, although you might already be doing this the screenshots don't show buffed or low health colors.
another thing id do is move the players in the spectator hud (the names on the left) more towards the vertical center of the screen, in these screenshots they are just slightly below being centered. again that probably doesn't make any sense and isn't helpful, so just move them upwards i guess.
on the loadout screen there are class icons, i'd say that making the spy his own face doesnt really work, and im pretty sure you could make it a knife and have it look quite a bit better, although this is probably another nitpick that doesnt particularly matter in the grand scheme of things.

things i like:

as mentioned previously i like the colors for buffed and low health in spectator
i also like what you've done for the specific classes in things like the class selection and backpack menu
i like the stats menu it looks really clean
i like the flat look of most materials, they look nice without using gradients or anything like that
for whatever reason i really like the default disguise menu, no clue why

thats all the feedback i have about the hud, feel free to disregard any/all of it as i'm not particularly good at tf2 and haven't actively played tf2 competitively outside of a few moments with friends. i'm also not very good at making huds and can only do a few things before asking for help so maybe i just don't know good ui design. hopefully this at least helped you in some way.