v3.26.1
Property, plant and equipment - Summary of Property, Plant and Equipment (Detail) - EUR (€)
 6 Months Ended 12 Months Ended
Jun. 30, 2026
Dec. 31, 2025
Disclosure Of Property Plant And Equipment [Line Items]    
Balance at beginning of period € 642,470 € 667,000
Additions 79,004 164,620
Depreciation expenses (175,699) (189,150)
Balance at end of period 545,775 642,470
Cumulative depreciation [member]    
Disclosure Of Property Plant And Equipment [Line Items]    
Balance at beginning of period (409,286) (220,136)
Depreciation expenses (175,699) (189,150)
Balance at end of period (584,985) (409,286)
Cumulative Costs [member]    
Disclosure Of Property Plant And Equipment [Line Items]    
Balance at beginning of period 1,051,756 887,136
Additions 79,004 164,620
Balance at end of period € 1,130,760 € 1,051,756