upgrading from LX 7.9 > LX 8.8 with SM web tier using Apache web server 9

hello

We are looking to upgrade our Linux servers runing the SM webtier, with Apache. we have SM 9.72 P1 

are there any best practices about upgrade the RHEL OS from 7 > 8  (or even 9), while the current SM webtier remains in place?

i know this is more or less RedHat related, but just wanted to know if anyone has experience here.

I know the OOB RH 8 does not ship with Apache. But what about upgrading? On the Apache side, is anything touched?

And what about running SM on RHEL 9? any better then 8? or no difference. or any pitfalls....

thanks for your tips.

PW