I understand exactly what you’re saying about harmony/Alexa and the awkwardness of the activity – based paradigm.
Just so you know, just a couple of weeks ago harmony did release a new “harmony red” skill which does let you do the equivalent of press a button for a few specific buttons: play, pause, mute, volume up, volume down, skip ahead, and skip back.
It won’t help with your lift chair project, but it’s really nice for home theater equipment.
You should definitely check it out. 
Meanwhile, yet another alternative would be a global cache IR controller. There are some people using these with SmartThings, but the integration is a lot more work to set up than the harmony. But you get granular control of the I R commands.
That one typically costs about $115 for the IR bridge, but most people then also buy some software to go with it. HAMbridge for $29 will work if you work if you have a mac to run it on. Or you can go with simple control (used to be called roomie remote) which is tablet-based, but that one requires an annual subscription fee.
https://www.amazon.com/Global-Cache-WF2IR-iTach-Wi-Fi/dp/B0051BU418
HAMBridge
Simple Control
They have their own rebranded version of the global cachet which costs about five dollars more, so say $120. But then you also need to buy a subscription of at least $50 a year and maybe more depending on the number and type of devices you’re using.
People who have the money seem to really like the simple control devices and system, but there’s no question that it’s an expensive option. Setup is much simpler than most of the other choices, though.