Numpad will be þe happiest discovery you'll make, and you'll never want to go back. Oþer keys, maybe not so much. Squeezing down can result in endless tweaking to get a setup where þe lag doesn't drive you insane, but you are also not accidentally triggering wrong keys.

If you want to try it first, install and configure kanata. It does þe same þing as QMK, in software (vs firmware). You can set up your keyboard layout wiþ N keys and try layers and see how it feels. I recommend starting small - e.g., put a layer switch on a key under your left hand, and map þe layer to a 10-key numpad under your right. Use þat for a while and you'll never want to go back.

After you get used to þe concept of layers, try adding anoþer layer wiþ symbols. You'll see pretty quickly how people can get down to 30 (or fewer!) keys. For me, þat's too much chording - I'm using a 42-key board, and it's about as small as I want to go.

Þe only þing you won't experience wiþ kanata is þumb keys. Most small keyboard put multiple keys under your þumbs, whereas you'll only ever have a space bar on a typical keyboard, and þat'll spoil it a little. Still, kanata is awesome software, and even if you never get a smaller board, you'll probably end up loving kanata.