https://ancient-hebrew.org/studies-words/facts-about-kaneh-bosem.htm Is this in regards to the cannabis debate over it?

Lest any Cannabis lovers get too excited, the qâneh portion of this compound phrase seems to indicate the stem or stalk of a reed-like plant:

Brown-Driver-Briggs' Hebrew Definitions

1. reed, stalk, bone, balances 1a) stalk 1b) water-plant, reed 1c) calamus (aromatic reed)

If anyone has ever seen a full grown Cannabis plant it is difficult to imagine calling it a reed. It really looks more like a bush than anything. Cannabis is the top picture and Calamagrostis/Reed Grass is on the bottom.

If Cannabis is in view here (which seems unlikely) it would be specifically referring to the stalk of the plant and not the leaves or buds. The stalk or stem of Cannabis contains very little, if any, of CBD, THC, or any of the "desired" chemical compounds.

This is not to downplay the medicinal uses of the Cannabis plant but only to say it was unlikely to have been used in the concoction of Holy Anointing Oil for temple use. After all, why rub the Ark of the Covenant, the altar, the candlesticks, etc. with medicinal or psychotropic compounds?

Additionally, even if Cannabis is the referenced plant, the items to be used in temple worship and indeed the priesthood and the very temple itself are rendered obsolete by the advent of the Christ to whom it all pointed.

Christians do not make use of "holy anointing oil" to sanctify either items or people. Sanctification under the New Covenant is the work of the Holy Spirit. No Cannabis needed.

Is there any evidence that this phrase should be translated 'ganja'?

No.

Exodus 30:23 (ESV) reads:

Take the finest spices: of liquid myrrh 500 shekels, and of sweet-smelling cinnamon half as much, that is, 250, and 250 of aromatic cane (qənêh-bōśem)

The OP points out:

there is a speculation that kaneh bosem is a plural form of kaneh bos.

This is based, presumably, on a misunderstanding of the ending em on bōśem. This is superficially similar to the masculine plural -ı̂m ending in Hebrew. However, the term qənêh-bōśem is singular (i.e. 250 shekels-worth of q-). The letter m is part of the root bśm.¹ The word qənêh- (spelled qāneh when alone) is a common term for "cane" or "reed". The phrase, then, is literally "cane of spice". The second noun bōśem is taken attributively, hence "fragrant cane". "Bos" means nothing in this context.²

As for the actual plant referred to in Exodus, I will believe William Propp's account:

fragrant cane. Qənē(h) bōśem is also called qāne(h) haṭṭôb ‘the sweet cane’ (Jer 6:20; cf. Akkadian qanû ṭābu) and simply qāne(h) 'cane' (Isa 43:24; Ezek 27:19). Although reeds are found in Israel itself, it is clear from the prophets that this special cane, like frankincense, was imported "from a distant land." Of various grasses valued in Antiquity for their aromatic essences...the variety most familiar to my readers will be East Asian "lemongrass."

Propp equates the terms bōśem and beśem earlier in the verse (there constructed with "cinnamon"). The emphasis is on their fragrance; there is no evidence of psychedelic properties attributed these plants in the Exodus account.

1. Were it plural, it would be bəśāmı̂m.
2. The etymologically related botanical term is is not cannabis but balsam.

Here is a recent discussion on this from a few months ago: https://old.reddit.com/r/AcademicBiblical/comments/xoabeg/qanehbosm_possible_mistranslation/