I've had some success running nexusDB under wine.
I was able to set up a WINEPREFIX, follow the instructions here to get at wine's odbc management panel (by default it pipes into unixODBC, and as Macarse noted, that's a dead end), set up a DSN there and test that it could access the data.
The next thing I tried was installing win32 PHP and writing a quick and dirty test using odbc_connect. After wasting a good chunk of time accidently using the linux php binary and wondering why it couldn't use the (inbuilt on win32 ONLY) function odbc_connect, I did get it working.
HINT: To save yourself feeling like banging your head against a brick wall, remember that any attempts to run php scripts in this environment MUST look like this
WINEPREFIX=/home/you/yourprefix wine php c:\phptest.php
NOT
WINEPREFIX=/home/you/yourprefix php c:\phptest.php
The second version will use the linux php binary. Feeling pretty stupid after running the second version a good dozen times AND googling the error some before realising what was wrong - I think I need to get up later if I want to be able to still make things work at 4am :(
(the c:\ path in the above examples can be passed as /home/you/yourprefix/drive_c/whatever
if you prefer - relative paths are also fine)
And yes, I know this is a necro post, but it's a pretty niche situation, there isn't a lot of information out there making nexusdb and odbc play nice on linux, and if this information was available to me a few months back when I was googling around and came across this thread it could have saved me a good chunk of time. Hope someone else finds it helpful.