Which M365 and Azure certs are worth pursuing?

Start with the work you want to be hired to do. AZ-104 is a solid choice for Azure administration, and SC-300 is worth considering if identity and access are a big part of the role you're aiming for.

I'd also check a bunch of relevant job postings before settling on a list. A cert that matches both your experience and the jobs you want is likely to be more useful than collecting whatever sounds popular.

Don't rule out AZ-900 and SC-900 just because they're fundamentals. They can be useful starting points if you want to refresh the basics of Azure and security before tackling a more specialized certification.

Check the current Microsoft certification pages before committing to MS-102. There was a claim that it's retiring, but there was also confusion about whether that meant MS-102 or MD-102. Verify the specific certification and any retirement date rather than assuming either one.

Since you aren't using Intune, I wouldn't make an endpoint management cert the first priority unless that's where you want your next job to take you. Pick the certs that reinforce the technologies you actually work with, or the ones you want to move into.