Bangladesh Bank may have declared cryptocurrencies to be illegal several times already but I still know a few people from there that do trade with bitcoins and fiat regularly. Having said that, the repercussions may not be that severe or that the ruling is not imposed heavily. Anyway, here's a good read on the current situation of bitcoin in Bangladesh although this appears to be an article from 2018. Not much has changed since then, still.
https://www.thedailystar.net/law-our-rights/law-analysis/bitcoin-legality-in-bangladesh-bank-1602583A quote from that same article:
The Foreign Exchange Regulation Act and Money Laundering Prevention Act contain provisions for punishment and criminal liability, for trading, importing, and exporting currencies without authorisation of the Bangladesh or if not performed through an authorised dealer, and for illegally laundering proceeds of crime or foreign currency. The definition of currency is given in section 2(b) of the Foreign Exchange Regulation Act, which includes:
(i) all coins, currency notes, bank notes, postal notes, money orders, cheques, drafts, traveler's cheques, letters of credit, bills of exchange and promissory notes; and
(ii) such other similar physical or non-physical instruments, or both as may be notified by the Bangladesh Bank from time to time;”
This may just mean that there is a slim chance of BB accepting cryptocurrencies and bitcoin in the future due to the inclusions of the Act fitting the definition of bitcoin and other crypto quite nicely. In the mean time, I would rather not get my hopes up and pray for the tides to turn, but there is always a ray of hope for our Bangladeshi brothers and sisters.