Slim kiosk setup for my kitchen dashboard on Raspberry Pi

I have a Raspberry Pi Monitor on my kitchen wall, driven by a Raspberry Pi. It shows a simple webpage, fed via MQTT with data from my smart home automations: the current house power consumption, the outside temperature, the temperature in my office, my car’s remaining range, and so on. That’s all it does. Recently, the SD card in its Raspberry Pi 3B died, so I had to reinstall it and took the opportunity to switch to a Raspberry Pi 3A+. And because the whole job is showing a single webpage, I wanted the setup reasonably slim: no desktop environment, just X and a browser.