“A fairer fight”? It would have been a bloodbath.
Of course, it's not realistic that the civilian populace will be capable of engaging in open-field combat with the military.
With these advantages and coordinating securely being generally available, I think an insurrection could create a lot of troubles for an occupying force. Lots of opportunities to document and share atrocities the occupying forces would commit as well which would at the very least ensure sympathetic governments and organizations would help continue the smuggling in of supplies and weapons.
The Chinese government in a few steps:
1. Cut off the internet, jam the radio signals and the satellite signals to blackout the entire island. Impose a sea blockade.
2. Stop the drinking water.
3. Wait 72 hours and gather the bodies. Blame local terrorists for destroying the water pipes.
And this is only the simplest way to smash the resistance. Without mobile communications and GPS, all groups will be cut off from each other, exposed from the air to drone attacks, and totally unable to retreat, because there is nowhere to go.
A better counterfactual case study would be North Korea, Nazi Germany, Soviet Russia or present-day Myanmar; where the regime largely lives amongst (albeit in a stratified/segregated way) and selects from the populace that it controls.
I'd be especially interested in the early days of the regime, before its power is fully solidified and when it's the most unstable.
Nazi Germany was like present day Russia - formerly authoritarian state that lost a big conflict, had democratic transition which was shaken by a series of economic crises. A large part of the population considered the strong leadership and revanchism for embodiment of the national essence. The economic elite welcomed the predictability of a well-oiled corrupt regime.
History of North Korea is not my strong side, but the North had huge chinese and soviet backing during the war while the South part was a military dictatorship until the nineties.
Myanmar military is maybe the most interesting of all these cases because this is not a regime with an ideology. Its backing is purely economic by Japan and China who have financial interests in the country, and the army officers internally, who can profiteer from an army-owned economy. For sure, there is some jingoism used by the army's propaganda; however, I don't follow the conflict and narratives there to assess properly what's going on there. However, as far as China is ready to sell the regime weapons and the regime has access to enough money to by them, the protests are doomed. Having access to power is existential for those guys and they won't let it go. Best scenario is if Japan and maybe China broker some deal "amnesty for democracy", but I doubt that they have the motivation to do so.
My mental exercise means to show that a highly nationalistic totalitarian regime which believes in itself and is faced by an existential threat will not hesitate to create a bloodbath. The communist regime can't afford to loose HK because "losing face" won't even begin to describe the situation. What's more, HK is not a defensible strong point. It can't ensure its supply lines and is dependent for its drinking water. Its enemy is a few kilometers away and has the second biggest fleet in the world.
What HK has is soft power. It is a free trading zone that has benefits granted to it by the US government, and it has its reputation. However, the chinese government proved that it is ready to throw all these advantages to enforce its control over the island and to unify its nationalistic narrative. Therefore, this soft power is good for nothing.
So yeah, there’s certainly Internet tough guys who just need an outlet to express their frustration. But there’s a large community of people that do in fact know which direction to point their rifle.