Hi @Federico Coppola ,
Per my test, the powershell would not hide the Power Apps button. In fact, when executing the command it will hide the action “see all apps” but not “Customize forms”. "Customize forms" could not be hidden.
And to make this only on subsite level, you could use the below command:
connect-pnponline https://tenant.sharepoint.com/sites/test/subsite
$ctx = Get-PnPContext
$ctx.Web.DisableAppViews = $true
$ctx.Web.DisableFlows = $true
$ctx.web.update()
$ctx.ExecuteQuery()
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