Embedded tech here! There are many ways to get started but since you seem to be interesting in the practical, modern, IoT centric way it makes things a lot easier.

This is all quickly typed on mobile:

The first thing to do is to check out this online simulator and get a sense of basic circuit theory: https://www.falstad.com/circuit/

The first thing not to do, is to buy a bunch of random junk. Buying stuff is a fun hobby but it is very different from actually doing projects and learning!

You will probably want a good multimeter, but I can't recommend a good affordable one. They are all pretty OK these days, but the current "Really nice one everyone likes" changes every few months or so as they change the models. Probably all the same chips inside...

You'll probably want an ESP32 development board with USB-C, some random sensor modules, whatever happens to interest you, maybe some relay modules, etc.

After that, you'll want to try out some breadboard projects, but I think you might quickly want to move on from that, and start doing PCB design. It's so cheap and easy these days.

and a soldering iron. I suspect you will want a Pinecil, and the thumb screw upgrade for said pinecil. I have a similar one but haven't tried the pinecil itself, this stuff changes fast. It's about $25.

SMD breakout boards are a good way to learn surfaces mount soldering while still doing breadboard stuff.

Eventually you'll want to do a project with just a bare microcontroller, if you're serious about learning. I don't ever actually do this in real life because I don't do high volume work, and IMHO using modules just makes so much more sense if you're making 10 of something custom that's hand-assembled.

But I'm glad I know how to, even if I don't generally need to.

You do not need a bench supply till you get a bit more advanced, very basic stuff can all be done on USB.

If you really are serious about this stuff, you're probably gonna want to learn some math if you're not already a math person, and maybe look into FPGA work, because there seems to be lots of jobs these days doing pretty high end advanced stuff.

A Coffee machine microcontroller seems like a simple enough starting point.

Stuff to consider:

How will you interface with the machine? Will you be switching 120vac? That of course requires lots of caution and you shouldn't mess with it till you actually know what you're doing.

But there are power strips with control voltage inputs that essentially abstract away the dangerous part in a professionally made box.

For an SMS controlled bot, you have a couple challenges that are all pretty independent.

First you need a source of power, and protection and charging for said power. I like to just use modules for that, but it might be fun to do that yourself on a PCB.

You need motor drivers and motors.

You need the mechanical side, for me this would be the hard part.

You need a microcontroller, and some kind of modem. They don't have to be on the same device, maybe you have a 4G gateway device that sends commands over WiFi to the bot, or maybe it's all onboard.

There's always lots of possibilities. Modern tech is basically just tiny computers with different IO, and computers allow a ton of creative freedom.

And you need to figure out how it all connects. Will you breadboard, use modules and jumpers, or go straight to a PCB design?

Once you generally know how electronics works(A simulator will greatly aid this), pick a project, pick a subsystem, and research all the ways that subsystem could be implemented.

I started pretty much just by jumping in. Arduino is the classic place to start and it's pretty nice. PlatformIO is even better these days.