WordPress multi site multi tenant questions

Hi guys I need some very high level architecture discussions. We are designing a multi tenant Saas solution. And trying to decide if WP is even doable or advisable.

Ok here goes
Multi tenant with multi site 98% web site vs blog.

So our clients would have have need single back office that could support multiple lead generation style websites or landing page systems. The tenant/client would have limited configuration options with these highly templeted landing page sites. I.e. Domain, copy, etc. layout would be fixed. The back office would have an Ecomerce ability if the tenant wants to purchase more options. = sites and functionality.

All tenant suites would be 100% identical with same options.

The top level prospects coming to these pages could have one level deep of a login experience.

So to add more context
Our clients are non technical savvy real estate agents who need lead generation solutions landing page sites.

The public would come to these sites and potentially create and account to gain further access to lead magnets and usability. Think a site where you search for homes and to save your search requires a login.

At the extreme back end we need to manage the entire system.

What are your thoughts ?
It's like a multi site with limited multi site. We can imagine the top level landing page sites will be ever high traffic. Also we have been developing the landing page sites in Php.

Thank you
Ottawa Canada.