Re your laptop "doesn't have any room"---you might be able to add memory if you haven't maxed it out already.
Wilcom has TrueSizer Web that might be useful. Free?
Touch Embroidery is an App for Android. $3. They have a free one as well -- but it doesn't have all the features.
If you have an iPad there are other options as well.
I should mention I have not used these.
Hmmm...I think Janome has software for their Horizon machine that works with a Mac tablet...Accu-Edit and Accu-Monitor...Don't have Janome machine, but do know that if you get their new machine, it comes with a Mac Tablet...
I also have a tablet and the only thing I can do is download a design. I then send it to my desktop computer and work from there. A tablet alone will not help you with embroidery software.
I agree with graceandham.I am afraid you are out of luck with a tablet.
I haven't seen one and it may be because digitizing programs are huge and complicated programs that do lots of intricate things. They need big space to work.
I was afraid of that.. and my laptop doesn't have enough room for one and I've taken everything off of it.