I was using an X10 siren module which supports a high/low chime, but it mysteriously stopped working. Could be related to some electrical work on my house.

I've looked for an Insteon chime, but can't find one.

Someone suggested an on/off plug:

Insteon

On/Off Plug

Controls plug-in lamps, space heaters, fans and other small appliances up to 15 Amps or 1800 Watts. Works with Amazon Alexa for voice control when paired with an Insteon Hub 2.

but I don't see a way to connect to a chime.

Important features for me:

Trigger a brief chime noise from eISY.

Preferably have two different pitched tones available.

Any recommendations?

I had one of those X10 modules as an alert for an automated garage door before closing it.

The Insteon on/off plug, like most Insteon device can be sent a message that will create a very brief, kind of quiet "cheep". It's meant more for diagnostic use to know that the switch is being linked or has a problem. It also can be used in debugging iox programs.

Insteon makes this siren module. It has 2 responses: It can make a door bell-ish ding dong like walking in a store, or a screamy siren sound that has scared my family members, pets and probably the plants.

It's not clear from the post about the continued role of X10. I don't think the current release of Insteon products respond to X10 any longer.

I have one of the early released Insteon Siren modules and I believe X10 was not supported.