How to say no to invitations during Lockdown 2.0

The pandemic is challenging our perceptions of etiquette when it comes to invitations.
Irish people are both really, really nice and cryptic masters of double speak. In Cork, “I will, ya” is one of the most dismissive things someone can say to you. Due to our chronic fear of saying no to requests, from something as simple as a cup of tea to as serious as becoming godmother to your sworn enemy’s firstborn, navigating the latest round of Government restrictions may pose some issues for us.
Even though we are allowed to create ‘bubbles’ and countrywide travel for weddings and funerals is deemed essential travel, some of us may not feel safe widening our circle or travelling cross-country. Is there etiquette established for saying no in these circumstances? If there is, what’s the best way to approach it?