Background/Objectives: The role of peroral pancreatoscopy (POPS) in patients with main-duct and mixed-type intraductal papillary mucinous neoplasm (MD/mixed-IPMN) remains unclear. This retrospective multicenter case series aimed to evaluate the feasibility and safety of POPS using the 9-Fr eyeMAX and to describe additional intraductal findings, potential surgical impact, and biopsy–surgery concordance. Methods: Consecutive patients with MD/mixed-IPMN in whom POPS was attempted between May 2023 and September 2025 were retrospectively analyzed. Pre-POPS imaging findings, POPS findings, procedural outcomes, adverse events, surgical outcomes, and concordance between POPS-guided biopsy and surgical pathology were evaluated. Results: Among the 20 patients, 14 were men, and the median age was 74.5 years (range, 46–83 years). IPMNs were classified as main-duct type in five patients (25%) and mixed type in 15 (75%). On endoscopic ultrasonography, mural nodules were identified in 14 patients (70%), with a median diameter of 11 mm (range, 3–25 mm). Endoscopic papillary intervention was performed in 6 patients (30%). The technical success rate of POPS insertion was 95% (19/20). Mural nodules were detected by POPS in 17 patients (85%), and biopsy under POPS guidance was performed a median of 5 times (range, 1–10). The adequate tissue sampling rate was 86% (88/102). Mild post-ERCP pancreatitis occurred in 1 patient (5%). Twelve patients (60%) underwent surgery. The concordance rate between POPS-targeted biopsy and surgical pathology was 45% (5/11); however, R0 resection was achieved in 11 patients (92%). Conclusions: In this small retrospective case series, POPS using the 9-Fr eyeMAX was feasible and provided additional intraductal information in selected patients. However, its diagnostic role remains adjunctive because POPS-guided biopsy showed limited reliability.