The likely project is a business-system re-platform, not a SharePoint lift-and-shift. Platform selection is an output of discovery—not its starting assumption.
Reconstruct what LASP actually did
A replacement cannot be estimated from product names alone. Discovery must map land, sales, approvals, documents, reporting, identities, exceptions and integration boundaries; distinguish intended workflow from accumulated workaround; and identify which historical behaviours still carry business or records value.
Test the legacy failure hypothesis
TLS, certificate, identity, IIS, SQL or SharePoint failures may explain why controlled read access stopped working. Diagnosing that path can recover evidence and reduce transition risk, but continuity does not automatically determine the target architecture.
Prove the candidate set
Power Pages with Dataverse, model-driven Power Apps, SharePoint Online with Power Platform, a custom Azure web application and a hybrid transition are legitimate candidates. Each must be tested against security, records, integration, usability, performance, delivery capacity and whole-of-life cost.
Create a pricing-grade handoff
Phase 1 exits with current and target architecture, option analysis, proof results, ADRs, migration waves, acceptance criteria, dependencies, work packages and an estimation basis another team can safely price.