MIDI DIN to USB adapters are really cheap and I've never had a problem with even the most generic Amazon one.
You don't mention your level of MIDI expertise, but what you should probably know, if you don't, is that analog synths with MIDI outputs are almost always MIDI-out only, unless they're mad expensive and have motorized controls (or use digital pots to control analog hardware, which is vanishingly rare).
Of course, you might be able to send notes to the synth via MIDI if it's got onboard MIDI to CV conversion, but you probably won't be able to control your synthesis parameters with MIDI. Your mileage may vary and I could be wrong, and if it's a newer analog synth you might be able to do it. But mostly you'll be able to sequence notes from another device with it. No matter what, you'll probably have to spend some time with the synth's manual just to get it running. It's good nerdy fun though.
You could hook the wires from a MIDI cable to some ESP32 pins, read the MIDI messages and send them instantly through BLE to an iPad/MacBook.
An ESP32 board has the advantage of booting instantly, can be powered from a battery for a lot more time, can't cause SD card corruption, and is less susceptible to delays caused by the kernel scheduler.
