Honestly, that last one doesn't feel like that much of a stretch. The other stuff actually feels trickier in some ways. PDFs are, by definition, portable, and I can't think of a single actually indie game designer (I don't include relatively large middle-market companies like Monte Cook games and White Wolf in that assessment) who will fault you for simply buying their game once, and literally emailing the PDF to the other members of your group. It's kind of an honor system, with the understanding that there's a big difference between violating our intellectual property rights (this usually involves selling the game without our permission or distributing it via a download link for whoever stumbles on it to pirate with impunity) and simply using the product in a manner consistent with common sense usability and convenience. 

If you were playing in person, you wouldn't each buy a separate copy of the rulebook to reference (at least not normally) - you'd likely buy one, and keep it on the table for everyone's use. Especially these days, now that in-person meetings are inaccessible for a literal overwhelming majority of people for various apocalyptic and dystopian reasons, it would be unreasonable of me to demand you buy 5 copies of the same game for the purpose of one campaign or even a one shot. Heck, as much as I find Monte Cook Games' 100 dollar PDFs to be an inaccessible, gatekeepy, and overall kind of gross move (like one step from turning a game into an NFT or something) masquerading as "praxis," even they argue that the exorbitant price tag will be worth because they figure that multiple people will pool their cash and buy and share their product together. 

There are also plenty of indie games, including most of my own, that offer limited but regularly refreshed pool of community copies, specifically on itch.io, which you can download for free, no questions asked, honor system and all that. They are meant for people experiencing poverty or marginalized people in general, but I don't mind if someone occasionally grabs one just to demo a game, with the hope that they will eventually "return it" to the pool by buying a paid copy (most community copy pools add new copies every time a certain number of people buy a game at full price). 

So yeah, a PDF and your friends' email addresses are all you need for something like that.

As for actual Roll20 alternatives, unfortunately it's less cut and dry. Personally, I think many traditional "big name" games are barely designed to be played smoothly in person, let alone online, so no matter which service you choose, you're still not only wrestling with the tedium of keeping track of all the numbers and grid positions or whatnot, but also constantly having to deal with tech issues borne from that fact that you are likely using at least three different but interconnected platforms and technologies all at the same time. The latter kind of screws with me most, and makes me reluctant to play online, just because I am so tired of players getting cut off during an important story beat, and us not realizing that this happened until five minutes later, or them still having audio output but no input, so they keep talking for 10 minutes before they realize that everyone isn't being really rude but just aren't hearing them, and so on. But this is the world we live in, so it's really part of the bargain until the technology itself improves sufficiently (which I am not optimistic about - I kind of think we're close to hitting diminishing returns). 

Currently, the only things I can think of are exactly the same that you'd get by googling "roll20 competitors" and checking on the first page of result. I haven't tried all of them, but I imagine they all have their strengths and weaknesses and none are perfect all of the time for any one person. Is the lag on the connection end or the voice client's end? If the latter, you can always try using a different service for voice while still using TTS.

At this point, I am personally hesitant to play anything online if it can't simply be played in a discord room without additional software running.