What can I use in future instead of Publisher

Why not install one of the other old standalone versions of Office on an old machine(that does not use 365) .Or better yet, install it in a VM on your daily.
driver.. I have Windows 7 working in a VM and very seldom use it, but it sure comes in handy for all kinds of uses when I do need it; creating themes, run old games, run some other ancient software.

I’d be surprised if there were many Publisher documents that I couldn’t reproduce in Word.

Screw it! I paid for it, I'll keep it running! And, yes, Publisher does run independent of the 2024 version! Tricky but legit!

Word is the best match to your requirements "mainly text with the odd graphic" and I guess will be around forever.
OpenOffice and LibreOffice are possibilities.
I stopped using MS Publisher a while back, tried Scribus not really impressed by that.

Everything now either MS Word or OpenOffice Writer/Draw.

Your stated requirements never required the use of a DTP product like MS Publisher which you have become very familiar with.
So it will be a learning curve to do the same thing in Word.