Table of Hardware: Ideal for OpenWrt confuses me

Hardware Questions and Recommendations
1

I asked about a sysupgrade problem I have.

I was told those routers aren't upgradeable to 19.07.4. I was told I should ask for buying recommendations here, and told I should look at https://openwrt.org/faq/which_router_should_i_buy which I did. It points to https://openwrt.org/toh/views/toh_available_16128

Table of Hardware: Ideal for OpenWrt (16/128MB or more)
[…]
129 WiFi Router GL.iNet GL-AR300M	v1.4.0 Available 2020 19.07.4
[…]
133 Travel Router GL.iNet GL-AR750S	v1 Available 2019 19.07.4

How do I make the most of that table?

2

Before asking on the forum: Please think about your requirements and provide answers to these questions. (We're going to ask them anyway, so save everyone time by doing this first. Thanks.)

What are your requirements?

By further filtering for your requirements.
Maybe I don't understand your question...

3

What are your requirements?

I want to buy dozens of identical tiny routers with 2 or 3 Ethernet ports with tagable switchports and/or interfaces and 2.4GHz WiFi. It should be easily available within the EU market. Detachable antennas are a huge plus. 5GHz WiFi is a plus. Gigabit Ethernet is a tiny plus. The device should be upgradeable to a vanilla OpenWrt for a long time. I don't want a zoo of different UIs in the field.

How do I make the most of that table?

By further filtering for your requirements.
Maybe I don't understand your question...

The table says explicitly the GL.iNet AR750S and GL.iNet AR300M are supported with version 19.07.4. That's why I bought test pieces. The older batch of AR300M were upgradeable through their bootloader at least. Newer aren't. Neither is the AR750S upgradeable. That's what I was told.

But the table says they are. How do I really know if they are?