As mentioned the buttons are made by E.A.O and you can easily replace the push buttons with the right tool.

You can look up the available buttons from series 61 on their website. When navigating to a particular button: there are distribution partners in the bottom.

For instance these are the aluminium ones:
https://www.eao.com/en/search?q=61-9841

And on this page you can use the configurator to see what options are available:
https://www.eao.com/product/61-9841.0A~10-2J09.1062~51-486.036F~61-9933.0/pushbutton/en/leuchtdrucktaste-baureihe-51-25-mm-ausgeleuchtet-flach-1-oe-gold-ip65-universalanschluss-2-x-05-mm

In order to get the old one out, use these:
https://www.eao.com/component/61-9730.0/de/druckhaubenzieher

I tried to buy them this year as well and certain colours are hard to source.