Exhibit 2.1 CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY [***], HAS BEEN OMITTED BECAUSE 908 DEVICES INC. HAS DETERMINED THE INFORMATION (I) IS NOT MATERIAL AND (II) WOULD LIKELY CAUSE COMPETITIVE HARM TO 908 DEVICES INC. IF PUBLICLY DISCLOSED. Share Purchase Agreement dated as of May 4, 2026 | by and among | | | --- | --- | | Florentin Coppey | (FC) | | Somlaproz 23 | | | 1937 Orsieres | | | Switzerland | | | and | | | Pierre Esseiva | (PE) | | Rapille-Dessus 5 | | | 1312 Eclépens ...