Be aware that many remote manufacturers are very open about their control. They can control almost anything, but many product manufacturers are very VERY proprietary in what they will allow for control. So, one manufacturer will have an open and published API and will work with many remote companies without issue. They work with both Google Home as well as Alexa and Apple. They should publish a list of the companies that they work with and how well they play with those products. Then you can do some digging to find out if they actually work well or not.
I am constantly blown away by people who say that 'Crestron is a locked control system'. It is, in reality, one of the most open because you can write modules for it that communicate via RS232, RS422, IP, infrared, and more. But, many companies don't publish their user interface and you end up not being able to control the device. Go figure.
But, if I were to recommend a solid user programmable remote control, it would definitely be Harmony.
I'm not sure if you already bought a bunch of Leviton switches, but I would reach out to them BEFORE you buy them and ensure that they have partnerships with Harmony and other universal remote control companies to allow for control of their product. To put this in perspective, Leviton TALKS about partner integration, but then doesn't actually have a page that lists the partners they actually integrate with.
Lutron Caseta, by contrast:
https://www.casetawireless.com/works-with
It clearly works with Logitech Harmony remotes and a long list of other products.