It's normal to be compensated for this.
At Google my team got $1600/wk because of the required SLA. At a startup I worked at, we didn't get paid extra, but we got an extra day of PTO for every week on call. (This is technically pointless, as we had unlimited PTO, but we did the rotation Thursday-Thursday and specifically didn't have meetings etc. on Friday so that the 2 people that were oncall last week could take a day off and not miss anything.)
Frankly, I preferred the cash. Many people on the team didn't want to be oncall, and so that meant more money for people that didn't mind, like me. It was good at the time, but certainly not for everyone.
Big companies with critical services do 24 hour oncall by having 3 offices and by having the oncall folks only be on call for their normal 8 hours. (12 hours is also somewhat do-able.) Even with this setup, extra compensation is expected. You can't go for a walk, or take lunch away from a computer, see your doctor, etc. And, you probably weren't going to work the weekend. So even 8 hours oncall requires compensation. I believe the Google SRE book goes into detail on the strategies that Google uses; SRE teams and SWE teams have different models.
At startups, this doesn't really work, because you're by definition a big company by the time you have 3 offices with dedicated SRE teams. (These places might call themselves startups so they can underpay you, but ... they're not.)
If I were starting my own company and needed oncall, I'd just expect that the founders/executive team take on the off-hours duties. You're the one whose company goes out of business if you have a bad outage. Being mad at some underpaid software engineer after the fact doesn't bring your customers back. And basically, it's unreasonable to ask people to be oncall. Some people with no life will do it, and they appreciate the cash, but other people literally don't have the ability to be available 24/7 unless you hire them an employee to take care of their kids or sick relatives or whatever.
With tech looking like a seller's market again (thanks AI!), I don't think you'll be able to build a team of talented and experienced developers if you require oncall. So get ready to do it yourself, or pay accordingly.
It would be informative if someone made a list like the extended exercise window list [1] for on call practices and comp if it exists
However one piece of conventional wisdom - on call rotations should be no less than eight people, and not much more. Going on call any more than one week in two months leads to burn out. Any less frequently than that you risk losing familiarity with on call procedures, the observability systems, etc.