Emerging embedded platforms increasingly rely on heterogeneous processing units to address diverse performance and energy requirements. The recently introduced AMD Embedded+ architecture reflects this trend by interconnecting via PCIe on the same motherboard one AMD x86 host processor with one Arm AArch64+FPGA complex. This implementation is another step forward towards a more compact heterogeneousISA platform designed with embedded applications in mind. While cross-ISA execution has been explored in the past with a focus on performance, programmability, and energy efficiency, its potential for embedded and predictable real-time workloads remains largely unexplored. In this paper, we start exploring such potential by investigating the real-time capabilities of the first commercial platform based on the AMD Embedded+ architecture: the Sapphire Edge+. We (1) outline key research challenges and real-time use-cases, (2) discuss suitable software architectures for the use-cases and highlight associated trade-offs, and (3) report an initial assessment of the potential of such architectures and use-cases via an experimental evaluation of latency and bandwidth on the real hardware.