Ideally, no, no one gets excluded. But when you have limits, its okay to make sure certain people are prioritized. Someone who wants to come back can go to weekday masses, attend ZOOM mass, and pray, and learn. I’d expect most of them would be understanding that there are a few extra steps to attending mass these days. It sounds like anyone willing to follow the steps is not being excluded where you live. It seems that it may just be that they aren’t steps that you are willing to do. Inclusion needs to work both ways. You need to do what it takes to stay in touch with them too.
You said that the churches have more restrictions than required, and that the parishes are being callous. Keep in mind that in many places, they may need to have fewer than the “allowable” number of people because the layout of the church doesn’t permit required distancing. I was at a different parish this summer for one weekend. After mass concluded, the priest said that while the area now permitted gatherings of 100, the distancing requirements did not really realistically permit that in their church. He even demonstrated why with the pews. Also, certain groups such as “religious gatherings”, have their own additional rules not always disclosed to the public. Where I live, masks are mandatory (at mass, you only take them off for a brief time for the eucharist). The priest does not need to mask during the homily, but I did not know this until the first time I was back at mass, and the priest told us why he wasn’t wearing a mask. What I guess I’m getting at here, is that it may not be the bishop. He may be taking rules you don’t know about from the government or health officials.
Why not follow a parish on facebook, or read their bulletins online? If someone had been doing that in my parish, even if unregistered, they would have known about Christmas mass registration no later than anybody else. No, it’s not the diocese that is responsible to find you a mass. What are they supposed to do, keep a list of all parishioners, registered and non, along with the parishes and times they’d be willing to attend? You keep saying you want to attend mass, but you won’t make calls, and you won’t link yourself to a parish. You’re also only complaining now after 9 months, telling me that missing Christmas mass specifically is what is bothering you, but with the limitations in place being necessary (you said you are not a covid denier), you provide little reason why you should get a spot at the mass of your choice, over the people who are active in their parish, or at least planned in advance for the mass day we all knew was going to be brutal.
I think you’re less upset about mass, and more upset that things aren’t back to normal. Maybe it’s time to find a new hobby, if yours are all out because of the pandemic. Online mass will never replace real mass, any bishop who tries to claim otherwise after he pandemic is gone, and dispensations are lifted will need to answer to Rome, who have said time and time again, it’s no real substitute. Other things, yeah, they may continue online. Parties, school. It changed fast, but most of us knew these changes would happen eventually.