You're very welcome to run Portal alongside Apple Developer and public macOS betas.
However, please note that OS betas by their very nature are unstable, subject to change and can introduce new bugs, as such we cannot offer any guarantees your Portal experience will be a smooth one.
Should you run into any issues, please do let us know as we'd love to be across them.
If you are keen to get access to earlier builds of Portal that may fix some of these issues then please drop us a line at hello@portal.app and we can look at adding you to our own Portal beta program.