First, N88-BASIC runs on all PC-88. It's a japanese Z80 computer, but PC-88VA are 16-bit, like the PC-98 and wonderswan. Instead, PC-98 runs N88-BASIC(86), which is different. I think only the PC-98DO and DO+ are compatible with PC-88 spotting a seperate chip and not PC88-VA. So I'm wondering for a long time, are the x86 compatible PC-88VA, VA2 and VA3 able to run the N88-BASIC(86) PC-98 os and maybe be modded to open it's software/games?
Unlike often mentioned, the PC-98VA machines do not use a NEC V50 (μPD70216), but a derivative μPD9002. The V50 is based on the V30 (μPD70116) core which includes a full 8080 emulation mode (*1). The μPD9002 expands that for full Z80 compatibility, thus next to all Z80 based PC-88 software can run on the VA series.
More details at the Japanese wiki
Unlike the Question implies the BASIC for the PC-88VA is not the same as N88-BASIC(86). In fact, there are three different BASICs
The VA series is equipped with N88 BASIC V3 (*2), which is fully upward compatible to the N88 BASIC V1/V2 used at previous PC-8800 models. To my knowledge it is not a 8086 based BASIC, but a continuation of the 8 bit series. Though it contains several additions compatible to N88-BASIC(86), as well as improved support for Japanese character handling and DBCS. This is a disk based BASIC.
N88-BASIC(86) is a ROM BASIC for the PC-98 series. While technical related to GW-BASIC, it's quite different offering a high degree of compatibility with N88 BASIC (*3). AFAICT all sources can be read and used with N88 BASIC (ofc. sans extensions).
N88-DISK BASIC (86) is essentially the same, loaded from disk, but offers an enhanced character encoding, so conversion may be needed backward compatibility.
And then there is
- N88-DISK BASIC(86) for MS-DOS. It's for most parts the same as N88-DISK BASIC(86), but uses (again) different character encoding for Japanese text. This time it was changed to be compatible with common character handling under MS-DOS. While source can be read under certain circumstances, all data files must be converted between the versions.
[There was also a version for Windows 2.0, but that's more of a curiosity as it was not continued].
*1 - Plus a whole bunch of peripherals making it a SoC, similar to Intels 80186, just somewhat more PC compatible.
*2 - N88 BASIC in turn is related to N-BASIC of the PC-8001 as both are MS-BASIC. While fully upward compatible, it used a different binary format, so programs had to be exchanged using ASCII format.
*3 - N88 BASIC was far ahead of GW-BASIC, so just anything less would have been a huge step back, not exactly what Customers would have appreciated.