Is it realistic to start piano at 35

Yes, with the caveat that adults quit for reasons children do not: impatience with the first plateau, and practice sessions scheduled at the end of the day when willpower is gone. Twenty minutes in the morning beats an hour promised for the evening.

A digital instrument with headphones for volume, and a rug plus felt pads for the structure-borne noise that headphones do not solve. The complaints are usually about thumping through the floor rather than the sound in the air.

When you stop noticing it. If it has not surfaced a problem in six months, it is either solved or it was never the bottleneck you thought.