These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 1.12 s (backtrack: 0/20).

[ebuild  N     ] acct-group/tss-0-r3::gentoo  0 KiB
[ebuild  N     ] acct-user/tss-0-r3::gentoo  0 KiB
[ebuild  N     ] app-crypt/tpm2-tss-4.2.0:0/4::gentoo  USE="fapi openssl policy -doc -mbedtls -static-libs -test" 1977 KiB
[ebuild  N     ] app-crypt/tpm2-tools-5.7.1::gentoo  USE="fapi -test" 1643 KiB

Total: 4 packages (4 new), Size of downloads: 3619 KiB