While the out of the box profile hover card and popup card provide great functionality and very visually pleasing, organizations may desire, or require, more out of a user profile experience than what is provided.

On many of the employee portals, or intranets that I've been a part of, searching for, finding, and viewing people data has been a big piece and typically one of the most frequently used pieces of functionality. Typically this involves incorporating data from other LOB systems, or other unique profile attributes. One example might be a "personality profile" attribute(s), perhaps displayed using a graph or other visual cue. In the context of a Professional Services organization, an example might be key clients/customers or clients/customers served in the last x days (possibly sourced ultimately from some timekeeping/billing application). Finally an example might be more detailed data on projects, skills, languages that are already captured within the profile (or targeted to be within the profile) - such as links to project site/documents, etc.

The possibilities are endless.

I am aware of the profile card customizations as described here (currently in BETA): https://techcommunity.microsoft.com/t5/microsoft-search-blog/new-profile-card-customization-through-microsoft-graph-beta/ba-p/1216517

While I recognize Microsoft is taking steps towards customization of the profile experience, I think limiting it to a few pre-canned Azure AD attributes, and 15 text only custom attributes is a bit limiting. For example, I was able to get a custom "profile page" attribute to render within the SPO profile popup dialogue, but it rendered as text only, not clickable - which would require a user to copy the link, and paste it into address bar to navigate.

I suggest a way to customize a person profile page for a tenant that would allow a tenant to build custom SPFx Web Part(s) to provide a custom experience and allow that experience to be linked to from the out-of-the-box experiences (such as the popup dialogue in SharePoint Online). Perhaps Microsoft can support an pre-canned profile page, but allow this to be overridden allow orgs/tenants to pull data in from other other systems. Alternatively provide a way to more deeply hook into the out-of-the-box profile experience, such as custom tab(s) within the SPO profile popup (again, perhaps using SPFx developed solution).