Clients only IT admin died. Locked out of m365.

Anyone got any ideas for this? Going through verification process with Microsoft but it's moving sooooo slow. We recovered access to the DNS through GoDaddy finally and are trying to get into their 365 admin center. They don't do email through GoDaddy but if I start email service with GoDaddy and make a new admin account... Would I be able to log into their current tenant with the GoDaddy email admin account? Any other ideas on this? I looked into an m365 take over but couldn't do it since it's still technically 'managed' since the admin account exists but they don't know the password or have the 2fa phone number

(Also I know them not having a back up plan for this was a bad move on their part , they hired us specifically to recover stuff because he died if you're going to post what they 'should have done to avoid this' please save yourself the time and don't because we all know already thanks)