The limitation is from MediaWiki, not Pywikibot.

		'emailuser' => [
			'ip' => [ 5, 86400 ], // 5 per day per ip (logged-out and new users)
			'newbie' => [ 5, 86400 ], // 5 per day for non-autoconfirmed
			'user' => [ 20, 86400 ], // 20 per day for users
		],

Accounts with the noratelimit right should bypass those limits.

How could I request the noratelimit right?

That will vary depending on the wiki. On most wikis, it is part of the sysop and bot groups.

If your tool is sending the emails as the logged-in user via OAuth, each user would need the right on their account.

Could it be acceptable to add e.g. ?

		'bots' => [ 2000, 86400 ],

The bot group has the noratelimit right, so the limits do not apply to them.

Apparently the noratelimit right was removed from the group bots in Wikidata, see T258354 ?

Then you'll need to address your use case with the Wikidata devs.