OK, I found it easy enough to install RC1 on a beta of (March 30) Ubuntu20.04. The repo has RPMs but no Debs and I really did not like the look of the install script, run as root ? no thanks.
So, I converted the rpm to a deb with alien (fakeroot alien --scripts fpc-3.2.0-0.rc1.x86_64.rpm). Lintian found enough problems with the resulting deb to publish in a small paperback but it did install OK on my clean U20.04 vm. However, seems alien overlooked the dependencies so I found it necessary to "apt install binutils make gcc" before using apt to install the deb (remembering, of course to set an explicit path to the deb).
The result was a working compiler, so, I got confident and pulled down Lazarus trunk and, sure enough it compiled that fine too. Manually installed the fpc scr tar.gz and up came Lazarus in all its glory ! Did have a problem with running the default demo empty form in Lazarus but thats probably some Lazarus issue I have overlooked. Tomorrow's problem.
Posting this, as much as anything else, so other in the Debian fold can easily install.
Davo