Unofficial snapd repository for Amazon Linux 2

Do you have EPEL enabled on your machine?

Edit:

Checked on my AMZN2 system, things seem to work ok:

google:amazon-linux-2-64 /# yum repolist
Loaded plugins: langpacks, priorities, update-motd
216 packages excluded due to repository priority protections
repo id                                                                         repo name                                                                                             status
amzn2-core/2/x86_64                                                             Amazon Linux 2 core repository                                                                            25526
amzn2extra-epel/2/x86_64                                                        Amazon Extras repo for epel                                                                                   1
epel/x86_64                                                                     Extra Packages for Enterprise Linux 7 - x86_64                                                        13403+216
snapd-amzn2/x86_64                                                              snapd packages for Amazon Linux 2                                                                             4
repolist: 38934

And a snapd from that repo is properly listed:

google:amazon-linux-2-64 /# yum list snapd\*
Loaded plugins: langpacks, priorities, update-motd
216 packages excluded due to repository priority protections
Available Packages
snapd.x86_64                                                                                  2.51-1.el7                                                                            epel       
snapd-debuginfo.x86_64                                                                        2.51-1.amzn2.1                                                                        snapd-amzn2
snapd-devel.noarch                                                                            2.51-1.el7                                                                            epel       
snapd-glib.x86_64                                                                             1.58-1.el7                                                                            epel       
snapd-glib-devel.x86_64                                                                       1.58-1.el7                                                                            epel       
snapd-glib-tests.x86_64                                                                       1.58-1.el7                                                                            epel       
snapd-qt.x86_64                                                                               1.58-1.el7                                                                            epel       
snapd-qt-devel.x86_64                                                                         1.58-1.el7                                                                            epel       
snapd-qt-qml.x86_64                                                                           1.58-1.el7                                                                            epel       
snapd-qt-tests.x86_64                                                                         1.58-1.el7                                                                            epel       
snapd-selinux.noarch                                                                          2.51-1.el7                                                                            epel       

As mentioned before, you can install it passing the complete version information:

google:amazon-linux-2-64 /# yum install snapd-2.51-1.amzn2.1
Loaded plugins: langpacks, priorities, update-motd
216 packages excluded due to repository priority protections
Resolving Dependencies
--> Running transaction check
---> Package snapd.x86_64 0:2.51-1.amzn2.1 will be installed
--> Processing Dependency: snap-confine(x86-64) = 2.51-1.amzn2.1 for package: snapd-2.51-1.amzn2.1.x86_64
--> Running transaction check
---> Package snap-confine.x86_64 0:2.51-1.amzn2.1 will be installed
--> Finished Dependency Resolution

Dependencies Resolved

===============================================================================================================================================================================================
 Package                                        Arch                                     Version                                           Repository                                     Size
===============================================================================================================================================================================================
Installing:
 snapd                                          x86_64                                   2.51-1.amzn2.1                                    snapd-amzn2                                    16 M
Installing for dependencies:
 snap-confine                                   x86_64                                   2.51-1.amzn2.1                                    snapd-amzn2                                   2.8 M

Transaction Summary
===============================================================================================================================================================================================
Install  1 Package (+1 Dependent package)

Total download size: 18 M
Installed size: 52 M
Is this ok [y/d/N]: ^C