Go here and click the link in post #1. I can't get there from work because it isn't characterized, but it contains a spreadsheet of altimeter comparisons.
The Altus Metrum MicroPeak will do that (if the flight is 43 seconds or less - that’s how much data it can record). You need the data interface device to get the data out and a computer. The software is available for PC, Mac and Linux.
The PerfectFlite FireFly - WITH the accessory Field Data Display (https://www.perfectflitedirect.com/firefly-field-data-display/) reads out the flight time along with descent rate, coast time to apogee as well as apogee altitude and maximum speed in several different units.
The PerfectFlite pNut will give you a full flight’s worth of altitude vs. time history - through an accessory cable connecting to a Windows or Mac computer. You get the time from the graph this software creates.
The Adrel is the tiniest - it requires a Windows PC (and until they get the software signed a hack to bypass Windows security for any Windows versions newer than XP) to get the data out.
Probably the lightest device that will give you both altitude and flight time without needing some other device with which to read the data is the Jolly Logic AltimeterTwo.