trogau

You can query core, plugin, and themes individually, or check all at once.
It defines four new methods:
<ul>
<li>xmlrpcCoreUpdateCheck – checks core, returns true/false</li>
<li>xmlrpcPluginUpdateCheck – checks plugins, returns true/false</li>
<li>xmlrpcThemeUpdateCheck – checks themes, returns true/false</li>
<li>xmlrpcUpdatesCheck – checks all of the above, returns an array of trues/falses.</li>
</ul>
The plugin was created primarily for WPUpCheck (http://trog.qgl.org/wpupcheck/), a simple 
Windows application that remotely polls a WordPress site to see if updates are available.

XML-RPC Update Check

This plugin provides XML-RPC methods for checking the update status of WordPress websites.

KZeni

Disables the default notification emails sent by a site after an automatic theme and/or plugin update. Simply activate the plugin to disable these email notifications (allows failure notices through unless setting is enabled to disable these as well).
This is a simple & lightweight plugin that simply uses the official filters made available as of WordPress 5.5 to disable these email notifications upon activation. It does let update failure notifications through by default, but the Settings => General page has a setting to disable these as well.
Check things out on GitHub at <a href="https://github.com/KZeni/Disable-WordPress-Theme-and-Plugin-Auto-Update-Emails" rel="nofollow ugc">https://github.com/KZeni/Disable-WordPress-Theme-and-Plugin-Auto-Update-Emails</a>

Disable Theme and Plugin Auto-Update Emails

Disables the default notification emails sent by a site after an automatic theme and/or plugin update. Simply activate the plugin to disable these ema …

XML-RPC Update Check vs Disable Theme and Plugin Auto-Update Emails