It's important to remember reddit's own rise to stardom was off of bad changes made to Digg which the community hated as well as off centralizing and killing off individual niche forums and also it's free speech absolutism. So it's not that surprising some amount of people would as reddit calcifies and enshittifies further try and make the jump to yet another alternative. We've seen it with kids moving from Myspace to Facebook to Instagram and Tiktok as those platforms become mainstream, become full of adults, clueless and strange boomers, and enshittify in the chase for profits, to say nothing of the web culture impulse of jumping to something different, new and exciting.
To be fair the lemmy devs were trying to grow lemmy as a replacement for reddit and did heavily advertise it not as a Marxist or leftist space but as an alternative ecosystem so we could say it's suffering from success which is likely necessary. The lemmy devs were not going to keep their nlnet funding by remaining a niche place full of only Marxists forever and if they want to continue getting paid to develop lemmy full time and we want them to get paid a broader base of support was inevitable. At the very least they won't hardcode in anti-left stuff which cannot be said for the owners of just about every capitalist centralized social media in existence, at best on those they're just too cheap and lazy to censor the left or anyone else and are chasing growth so much they'll tolerate anyone who isn't pushing literal CSAM or ISIS propaganda.
To be fair Saw specifically says to Wilmon (who Luthen sends) in S2E05 during his rhydo speech thing about revolution not being for the sane, how "we'll all be dead before the Republic is back", now maybe he was just talking in broad terms of the goals of the others or has certain better ideas about what a new Republic should look like but it certainly sounded like the show writers were making it his goal too. He is one of the most revolutionary coded characters though.
Much as we might want to cast our wishes onto Andor there were never any strong mentions of left revolutionary thought (nothing that would be out of place in liberals talking about bringing down the USSR or Nazi Germany from the liberal perspective) and only vague baiting towards communism without so much as a solid two spoken lines of dialogue that suggests more than some aesthetics being adopted in the way liberalism tends to recuperate revolutionaries.
It was all about tearing down bad thing (Empire) and replacing it with either hand-wavy thing that isn't "authoritarian/dictatorial" or just straight up restoration of the Republic. Nemik in particular doesn't come off to me as spouting anything but liberal platitudes for the most part. None of them talk about broad, just about how the empire is bad and hurts people and walks around like a bully carrying out abuses. Nothing about economic systems, nothing about say promoting gender equality, racial/species equality, addressing any kind of structural issues in the Galaxy they live in. So we have little idea who they really are or what they'd do if they took power. You mention subordination to the goal of the revolution and fair enough but it's just a way to leave it open to paint it whatever color you want depending on your ideology unless you're a raving fascist freak who loves the empire of course.
It's all very liberal and VAGUE in that way, there's this big bad government (thankfully very fascist coded not communist coded) and it uses authority badly and abusively and does arbitrary executions and all kinds of just vicious repression and occupying power abuse stuff and they're against that and they get together with friends, do a little adventurism but a lot of it is idealistic speeches by the lib Mon Mothma and such that we're to presume opens a gas line to the revolutionary flame that gets the new recruits, welds the various factions together and sets things off for the events of the films.
In this way of keeping things vague people can see what they want. The can see the American revolution in it, they can see the French revolution, they can see the fall of the USSR to US backed protests and color revolutions as cast as "organic uprisings" by western media and history books, they can if they're leftists see the rise of the USSR against feudal Russia. They can see the empire as a "what if Nazi Germany succeeded" type thing.
I do agree about the killing off of radicals at least being potentially a kind of statement. As is the fact they try to rein them in but only because they fail does the rebellion succeed (if Luthen had thrown in the towel when they wanted they wouldn't have learned of the death star until too late, if Andor had been less of a rogue guy and obediently followed all his orders they would have been destroyed by not properly following through). Though ultimately it's not shown that this is anything other than luck and dedication, nothing ideological that sets Luthen, Andor, etc apart from the lib rebellion leaders cowering on Yavin.
It's definitely one of the most leftist, revolutionary shows from the west, in the English speaking world made in probably at least a quarter century (post 9/11), maybe longer because it can be interpreted that way and does critique fascism and have a lot of revolutionary spirit but by the last 4 episodes it does as you and others note cram itself back into Disney's timeline.