The Ukulele is a lovely instrument to introduce children to the world of playing music.
It is physically easier to play chords on the ukulele compared to other instruments.
There’s a lot of ukulele for beginner level that are reasonably priced, from € 50-100.

Types of Ukulele's : Soprano, concert, tenor, and baritone.
The Soprano, concert, and tenor size ukuleles are all tuned to standard tuning which is
G-C-E-A. Baritone ukuleles have a different tuning: D-G-B-E.
Some people find concert and tenor ukuleles easier to play than soprano ukuleles.
A soprano is the smallest. The nylon strings on the soprano ukulele beginner are easy to play​.
The concert Ukulele is a little bit bigger and produces a more rounded sound.
The tenor is bigger again and has a fuller sound and prefered by professional ukulele players.