solucionado instalando nodemon explicitamente.
Adicionalmente me ocurre lo siguiente continuando con el curso:
PS C:\Users\Ricar\Desktop\Curso\curso-typescript\src> npx tsc –init –outDir dist
Need to install the following packages:
Ok to proceed? (y) y
This is not the tsc command you are looking for
To get access to the TypeScript compiler, tsc, from the command line either:
– Use npm install typescript to first add TypeScript to your project before using npx
Lo he instalado igual que con el nodemon pero no me funciona.