Ubuntu 21.04 was released on 22 April 2021 with a load of new features. Wayland is now default. Your home folder is now private by default. There is a recovery key for encrypted installs and it comes with the Linux 5.11 kernel and Python 3.9. You can download it https://ubuntu.com/#download. There are also links to the Ubuntu flavors on that page. Remember that Hirsute Hippo is only supported for 9 months (January 2021) so if you are looking for a LTS release either stick with 20.04 or wait for the release of Ubuntu 22.04 (April 2022). By the way the release date for the next Ubuntu version (Ubuntu 21.10, Impish Indri) is 14 October 2021.
I was introduced to a multi-boot device back on 10 January 2015 by a post made on this website by gauchocollie. It was MultiSystem http://liveusb.info/dotclear/. I have used it since then on several USB flash drives at our installfests in Tempe and Sierra Vista. An AZLOCO and CLUG member and I were talking recently and he asked me if I had tried Ventoy https://www.ventoy.net/en/index.html. I tried it and it is easier to use and update than MultiSys. The features are listed on their website.
Just download the latest version, extract it, open a terminal, and follow the instructions on the document page. It is free and open source software and will work on Linux and Microsoft. Plus 90% of the distros on DistroWatch are supported. That is over 580 ISOs. If you are tired of carrying around multiple flash drives try this. You may find it useful.
Ubuntu 20.10, Groovy Gorilla, was released on 22 October 2020. It is available for download at https://ubuntu.com/#download. There are also links to all of the Ubuntu “flavors” on the bottom right side of that page as well as links to torrent downloads. Ubuntu 20.10 is not a Long Term Support (LTS) release and is only supported for 9 months.