If he just wants to buy a nice expensive .177 Target Air pistol.
First decide if you want an electronic trigger or not.
Then new or used.

Having a budget helps and stops you getting carried away.

You shouldn’t go far wrong with…..

Steyr EVO 10.
Steyr EVO 10e (electronic)
Feinwerkbau P8X.
Walther LP500.
Pardini K12.
Morini 162ei (electronic)

I have owned and shot all the above. They all shoot well.

With so many different sizes of grip, try not to buy anything that won’t fit.

Grips are now £150+