Setup highly available/redundant (multi-server) dynamic one-site hosting with whole server backups?

There are some steps on how to replace MariaDB by MySQL:

Though such replacement may cause issues as mentioned on same page under later post:

Another replacement steps:

https://blogs.oracle.com/mysql/post/how-to-migrate-from-mariadb-to-mysql-80 <<<<

It is worrisome for a layman needing to manually switch from MDB to MSQ. I am already having established site with populated database 10.6.18-MariaDB-cll-lve . My script provider is using MySQL, but told me i may stay on a MariaDB. So that may not be a big problem.

Can anyone please address the main questions in the 1st post of this thread regarding clustering/high availability? I would like to stay away from a load balancing setup with single load balancer (a signle point of a failure) and I think I would need a tutorial. Thank you in advance.